Attachment 360311 Details for Bug 192742 – Patch

[patch] Patch

bug-192742-20190127163035.patch (text/plain), 132.90 KB, created by Darin Adler on 2019-01-27 16:30:36 PST

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Creator: Darin Adler

Created: 2019-01-27 16:30:36 PST

Size: 132.90 KB

patch

obsolete

>Subversion Revision: 240556
>diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
>index ac6f664b5603569201ce01baada6b7f7b5defc42..848e889ac20541dcc52507926021e50433e5b8bf 100644
>--- a/Source/JavaScriptCore/ChangeLog
>+++ b/Source/JavaScriptCore/ChangeLog
>@@ -1,3 +1,29 @@
>+2018-12-15  Darin Adler  <darin@apple.com>
>+
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        * inspector/InjectedScriptBase.cpp:
>+        (Inspector::InjectedScriptBase::makeCall): Use makeString.
>+        (Inspector::InjectedScriptBase::makeAsyncCall): Ditto.
>+        * inspector/InspectorBackendDispatcher.cpp:
>+        (Inspector::BackendDispatcher::getPropertyValue): Ditto.
>+        * inspector/agents/InspectorConsoleAgent.cpp:
>+        (Inspector::InspectorConsoleAgent::enable): Ditto.
>+        * jsc.cpp:
>+        (FunctionJSCStackFunctor::operator() const): Ditto.
>+
>+        * runtime/CodeCache.cpp:
>+        (JSC::writeCodeBlock): Use makeString's numeric capabilities instead of
>+        using String::number.
>+
>+        * runtime/IntlDateTimeFormat.cpp:
>+        (JSC::IntlDateTimeFormat::initializeDateTimeFormat): Use string concatenation.
>+        * runtime/IntlObject.cpp:
>+        (JSC::canonicalizeLocaleList): Ditto.
>+
> 2019-01-27  Chris Fleizach  <cfleizach@apple.com>
> 
>         AX: Introduce a static accessibility tree
>diff --git a/Source/WTF/ChangeLog b/Source/WTF/ChangeLog
>index 6e84d9c1fcc59a99f414b93c6238f15e0e7d29a1..8c194658cd437e36d465a316b711a741c0020b6f 100644
>--- a/Source/WTF/ChangeLog
>+++ b/Source/WTF/ChangeLog
>@@ -1,3 +1,17 @@
>+2018-12-15  Darin Adler  <darin@apple.com>
>+
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        * wtf/WorkQueue.cpp:
>+        (WTF::WorkQueue::concurrentApply): Use makeString.
>+
>+        * wtf/dtoa.cpp:
>+        (WTF::dtoa): Use sprintf instead of String::format in the comments,
>+        since these functions have nothing to do with WTF::String.
>+
> 2019-01-25  Chris Dumez  <cdumez@apple.com>
> 
>         [iOS] Add support for the download attribute
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index d01af3391b6db0278d4f8dcd287e3d14474a6976..a84d95827589b40aa75412c28c895a5205fa7cbc 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,183 @@
>+2018-12-15  Darin Adler  <darin@apple.com>
>+
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        A while back, String::format was more efficient than string concatenation,
>+        but that is no longer true, and we should prefer String::number, makeString,
>+        or concatenation with the "+" operator to String::format for new code.
>+
>+        This is not as good for programmers who are fond of printf formatting
>+        style, and in some cases it's a little harder to read the strings
>+        interspersed with variables rather than a format string, but it's better
>+        in a few ways:
>+
>+        - more efficient (I didn't measure the difference, but it's definitely
>+          slower to use String::Format which calls vsnprintf twice than to use
>+          the WTF code)
>+        - works in a type-safe way without a need to use a format specifier such
>+          as "%" PRIu64 or "%tu" making it much easier to avoid problems due to
>+          subtle differences between platforms
>+        - allows us to use StringView in some cases to sidestep the need to
>+          allocate temporary WTF::String objects
>+        - does not require converting each WTF::String to a C string, allowing
>+          us to remove many cases of ".utf8().data()" and similar expressions,
>+          eliminating the allocation of temporary WTF::CString objects
>+
>+        This patch covers a batch of easiest-to-convert call sites.
>+        Later patches will allow us to deprecate or remove String::format.
>+
>+        * Modules/indexeddb/server/SQLiteIDBBackingStore.cpp:
>+        (WebCore::IDBServer::SQLiteIDBBackingStore::addRecord): Use makeString.
>+        * Modules/indexeddb/shared/IDBCursorInfo.cpp:
>+        (WebCore::IDBCursorInfo::loggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBGetAllRecordsData.cpp:
>+        (WebCore::IDBGetAllRecordsData::loggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBGetRecordData.cpp:
>+        (WebCore::IDBGetRecordData::loggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBIndexInfo.cpp:
>+        (WebCore::IDBIndexInfo::loggingString const): Ditto.
>+        (WebCore::IDBIndexInfo::condensedLoggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBIterateCursorData.cpp:
>+        (WebCore::IDBIterateCursorData::loggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBObjectStoreInfo.cpp:
>+        (WebCore::IDBObjectStoreInfo::condensedLoggingString const): Ditto.
>+        * Modules/indexeddb/shared/IDBResourceIdentifier.cpp:
>+        (WebCore::IDBResourceIdentifier::loggingString const): Ditto.
>+        * Modules/webdatabase/Database.cpp:
>+        (WebCore::formatErrorMessage): Ditto.
>+        * Modules/webdatabase/SQLError.h:
>+        (WebCore::SQLError::create): Ditto.
>+
>+        * bindings/scripts/CodeGeneratorJS.pm:
>+        (GenerateImplementation): Use makeString.
>+
>+        * bindings/scripts/test/JS/JSInterfaceName.cpp:
>+        * bindings/scripts/test/JS/JSMapLike.cpp:
>+        * bindings/scripts/test/JS/JSReadOnlyMapLike.cpp:
>+        * bindings/scripts/test/JS/JSTestActiveDOMObject.cpp:
>+        * bindings/scripts/test/JS/JSTestCEReactions.cpp:
>+        * bindings/scripts/test/JS/JSTestCEReactionsStringifier.cpp:
>+        * bindings/scripts/test/JS/JSTestCallTracer.cpp:
>+        * bindings/scripts/test/JS/JSTestClassWithJSBuiltinConstructor.cpp:
>+        * bindings/scripts/test/JS/JSTestCustomConstructorWithNoInterfaceObject.cpp:
>+        * bindings/scripts/test/JS/JSTestDOMJIT.cpp:
>+        * bindings/scripts/test/JS/JSTestEnabledBySetting.cpp:
>+        * bindings/scripts/test/JS/JSTestEventConstructor.cpp:
>+        * bindings/scripts/test/JS/JSTestEventTarget.cpp:
>+        * bindings/scripts/test/JS/JSTestException.cpp:
>+        * bindings/scripts/test/JS/JSTestGenerateIsReachable.cpp:
>+        * bindings/scripts/test/JS/JSTestGlobalObject.cpp:
>+        * bindings/scripts/test/JS/JSTestIndexedSetterNoIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestIndexedSetterThrowingException.cpp:
>+        * bindings/scripts/test/JS/JSTestIndexedSetterWithIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestInterface.cpp:
>+        * bindings/scripts/test/JS/JSTestInterfaceLeadingUnderscore.cpp:
>+        * bindings/scripts/test/JS/JSTestIterable.cpp:
>+        * bindings/scripts/test/JS/JSTestMediaQueryListListener.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedAndIndexedSetterNoIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedAndIndexedSetterThrowingException.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedAndIndexedSetterWithIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedConstructor.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedDeleterNoIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedDeleterThrowingException.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedDeleterWithIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedDeleterWithIndexedGetter.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedGetterCallWith.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedGetterNoIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedGetterWithIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterNoIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterThrowingException.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithIdentifier.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetter.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetterAndSetter.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithOverrideBuiltins.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithUnforgableProperties.cpp:
>+        * bindings/scripts/test/JS/JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins.cpp:
>+        * bindings/scripts/test/JS/JSTestNode.cpp:
>+        * bindings/scripts/test/JS/JSTestObj.cpp:
>+        * bindings/scripts/test/JS/JSTestOverloadedConstructors.cpp:
>+        * bindings/scripts/test/JS/JSTestOverloadedConstructorsWithSequence.cpp:
>+        * bindings/scripts/test/JS/JSTestOverrideBuiltins.cpp:
>+        * bindings/scripts/test/JS/JSTestPluginInterface.cpp:
>+        * bindings/scripts/test/JS/JSTestPromiseRejectionEvent.cpp:
>+        * bindings/scripts/test/JS/JSTestSerialization.cpp:
>+        * bindings/scripts/test/JS/JSTestSerializationIndirectInheritance.cpp:
>+        * bindings/scripts/test/JS/JSTestSerializationInherit.cpp:
>+        * bindings/scripts/test/JS/JSTestSerializationInheritFinal.cpp:
>+        * bindings/scripts/test/JS/JSTestSerializedScriptValueInterface.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifier.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierAnonymousOperation.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierNamedOperation.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierOperationImplementedAs.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierOperationNamedToString.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierReadOnlyAttribute.cpp:
>+        * bindings/scripts/test/JS/JSTestStringifierReadWriteAttribute.cpp:
>+        * bindings/scripts/test/JS/JSTestTypedefs.cpp:
>+        Updated expected results.
>+:
>+        * css/parser/CSSPropertyParserHelpers.cpp:
>+        (WebCore::CSSPropertyParserHelpers::parseHexColor): Use String::number
>+        and makeString.
>+
>+        * html/HTMLSelectElement.cpp:
>+        (WebCore::HTMLSelectElement::setLength): Use makeString.
>+        * html/ImageDocument.cpp:
>+        (WebCore::ImageDocument::imageUpdated): Ditto.
>+        * html/parser/XSSAuditor.cpp:
>+        (WebCore::XSSAuditor::init): Ditto.
>+        * inspector/InspectorFrontendClientLocal.cpp:
>+        (WebCore::InspectorFrontendClientLocal::setDockingUnavailable): Ditto.
>+        (WebCore::InspectorFrontendClientLocal::setAttachedWindow): Ditto.
>+        (WebCore::InspectorFrontendClientLocal::setDebuggingEnabled): Ditto.
>+        (WebCore::InspectorFrontendClientLocal::setTimelineProfilingEnabled): Ditto.
>+        (WebCore::InspectorFrontendClientLocal::showMainResourceForFrame): Ditto.
>+        * inspector/agents/InspectorCSSAgent.cpp: Ditto.
>+        * inspector/agents/InspectorIndexedDBAgent.cpp: Ditto.
>+        * page/MemoryRelease.cpp:
>+        (WebCore::logMemoryStatisticsAtTimeOfDeath): Ditto.
>+
>+        * page/cocoa/ResourceUsageOverlayCocoa.mm:
>+        (WebCore::formatByteNumber): Use String::number.
>+        (WebCore::ResourceUsageOverlay::platformDraw): Use string concatenation.
>+
>+        * page/cocoa/ResourceUsageThreadCocoa.mm:
>+        (WebCore::logFootprintComparison): Use makeString.
>+        * platform/animation/TimingFunction.cpp:
>+        (WebCore::TimingFunction::cssText const): Ditto.
>+
>+        * platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm:
>+        (WebCore::AVTrackPrivateAVFObjCImpl::id const): Use AtomicString::number.
>+        * platform/graphics/avfoundation/objc/MediaSampleAVFObjC.h:
>+        (WebCore::MediaSampleAVFObjC::MediaSampleAVFObjC): Ditto.
>+
>+        * platform/graphics/ca/GraphicsLayerCA.cpp:
>+        (WebCore::GraphicsLayerCA::setContentsToSolidColor): Use makeString.
>+        (WebCore::GraphicsLayerCA::updateContentsImage): Ditto.
>+        (WebCore::GraphicsLayerCA::updateContentsRects): Ditto.
>+        (WebCore::GraphicsLayerCA::createTransformAnimationsFromKeyframes): Ditto.
>+        * platform/mock/MockRealtimeVideoSource.cpp:
>+        (WebCore::MockRealtimeVideoSource::drawText): Ditto.
>+
>+        * platform/mock/mediasource/MockSourceBufferPrivate.cpp: Use String::number.
>+
>+        * platform/network/ParsedContentRange.cpp:
>+        (WebCore::ParsedContentRange::headerValue const): Use makeString.
>+
>+        * platform/network/cf/NetworkStorageSessionCFNet.cpp: Removed some unnecessary
>+        compiler conditionals and reorganized the start/stop of namespaces.
>+        (WebCore::NetworkStorageSession::switchToNewTestingSession): Use makeString.
>+
>+        * platform/sql/SQLiteDatabase.cpp:
>+        (WebCore::unauthorizedSQLFunction): Use makeString.
>+        * rendering/RenderLayerCompositor.cpp:
>+        (WebCore::RenderLayerCompositor::logLayerInfo): Ditto.
>+        * workers/service/server/RegistrationDatabase.cpp:
>+        (WebCore::RegistrationDatabase::ensureValidRecordsTable): Ditto.
>+        (WebCore::RegistrationDatabase::importRecords): Ditto.
>+
> 2019-01-27  Wenson Hsieh  <wenson_hsieh@apple.com>
> 
>         Remove a couple of PLATFORM defines intended for watchOS
>diff --git a/Source/WebKit/ChangeLog b/Source/WebKit/ChangeLog
>index 0ff7b88704f0ec203d8f50232360affb53f2a295..d93f9222892c3b5fa7a1195611a552d7e430bba7 100644
>--- a/Source/WebKit/ChangeLog
>+++ b/Source/WebKit/ChangeLog
>@@ -1,3 +1,22 @@
>+2018-12-15  Darin Adler  <darin@apple.com>
>+
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        * Shared/WebMemorySampler.cpp:
>+        (WebKit::WebMemorySampler::writeHeaders): Use makeString.
>+
>+        * UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm:
>+        (WebKit::LocalAuthenticator::makeCredential): Use string concatentation.
>+
>+        * UIProcess/WebInspectorUtilities.cpp:
>+        (WebKit::inspectorPageGroupIdentifierForPage): Use makeString.
>+        * UIProcess/WebProcessPool.cpp:
>+        (WebKit::WebProcessPool::processDidFinishLaunching): Ditto.
>+        (WebKit::WebProcessPool::startMemorySampler): Ditto.
>+
> 2019-01-27  Jiewen Tan  <jiewen_tan@apple.com>
> 
>         Use a load optimizer for some sites
>diff --git a/Source/WebKitLegacy/ChangeLog b/Source/WebKitLegacy/ChangeLog
>index a6a58c4e93d6c29678bec41fbdf1a104f8888ef5..d9590d8d0e60c982957d51e287a41129c7d078a6 100644
>--- a/Source/WebKitLegacy/ChangeLog
>+++ b/Source/WebKitLegacy/ChangeLog
>@@ -1,3 +1,22 @@
>+2019-01-26  Darin Adler  <darin@apple.com>
>+  
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        * Shared/WebMemorySampler.cpp:
>+        (WebKit::WebMemorySampler::writeHeaders): Use makeString.
>+
>+        * UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm:
>+        (WebKit::LocalAuthenticator::makeCredential): Use string concatentation.
>+
>+        * UIProcess/WebInspectorUtilities.cpp:
>+        (WebKit::inspectorPageGroupIdentifierForPage): Use makeString.
>+        * UIProcess/WebProcessPool.cpp:
>+        (WebKit::WebProcessPool::processDidFinishLaunching): Ditto.
>+        (WebKit::WebProcessPool::startMemorySampler): Ditto.
>+
> 2019-01-24  Ross Kirsling  <ross.kirsling@sony.com>
> 
>         Move FileSystem to WTF
>diff --git a/Source/JavaScriptCore/inspector/InjectedScriptBase.cpp b/Source/JavaScriptCore/inspector/InjectedScriptBase.cpp
>index 91d0c7fb175001aec6fcf6579b080af4bb3a8468..fd8bbcf06f00b1877dfa66075e2d5a2811161cba 100644
>--- a/Source/JavaScriptCore/inspector/InjectedScriptBase.cpp
>+++ b/Source/JavaScriptCore/inspector/InjectedScriptBase.cpp
>@@ -40,7 +40,7 @@
> #include "NativeStdFunctionCell.h"
> #include "ScriptFunctionCall.h"
> #include <wtf/JSONValues.h>
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace Inspector {
> 
>@@ -91,7 +91,7 @@ Ref<JSON::Value> InjectedScriptBase::makeCall(Deprecated::ScriptFunctionCall& fu
> 
>     RefPtr<JSON::Value> resultJSONValue = toInspectorValue(*m_injectedScriptObject.scriptState(), resultJSValue);
>     if (!resultJSONValue)
>-        return JSON::Value::create(String::format("Object has too long reference chain (must not be longer than %d)", JSON::Value::maxDepth));
>+        return JSON::Value::create(makeString("Object has too long reference chain (must not be longer than ", JSON::Value::maxDepth, ')'));
> 
>     return resultJSONValue.releaseNonNull();
> }
>@@ -122,7 +122,7 @@ void InjectedScriptBase::makeAsyncCall(Deprecated::ScriptFunctionCall& function,
>             if (auto resultJSONValue = toInspectorValue(*exec, exec->argument(0)))
>                 checkAsyncCallResult(resultJSONValue, callback);
>             else
>-                checkAsyncCallResult(JSON::Value::create(String::format("Object has too long reference chain (must not be longer than %d)", JSON::Value::maxDepth)), callback);
>+                checkAsyncCallResult(JSON::Value::create(makeString("Object has too long reference chain (must not be longer than ", JSON::Value::maxDepth, ')')), callback);
>             return JSC::JSValue::encode(JSC::jsUndefined());
>         });
>     }
>diff --git a/Source/JavaScriptCore/inspector/InspectorBackendDispatcher.cpp b/Source/JavaScriptCore/inspector/InspectorBackendDispatcher.cpp
>index 5cbc0da9df474a13abae711179ae3d5de11c294c..fdefd42ceb37b0b72431205b8a1164d7408d07dd 100644
>--- a/Source/JavaScriptCore/inspector/InspectorBackendDispatcher.cpp
>+++ b/Source/JavaScriptCore/inspector/InspectorBackendDispatcher.cpp
>@@ -289,19 +289,19 @@ T BackendDispatcher::getPropertyValue(JSON::Object* object, const String& name,
> 
>     if (!object) {
>         if (!out_optionalValueFound)
>-            reportProtocolError(BackendDispatcher::InvalidParams, String::format("'params' object must contain required parameter '%s' with type '%s'.", name.utf8().data(), typeName));
>+            reportProtocolError(BackendDispatcher::InvalidParams, makeString("'params' object must contain required parameter '", name, "' with type '", typeName, "'."));
>         return result;
>     }
> 
>     auto findResult = object->find(name);
>     if (findResult == object->end()) {
>         if (!out_optionalValueFound)
>-            reportProtocolError(BackendDispatcher::InvalidParams, String::format("Parameter '%s' with type '%s' was not found.", name.utf8().data(), typeName));
>+            reportProtocolError(BackendDispatcher::InvalidParams, makeString("Parameter '", name, "' with type '", typeName, "' was not found."));
>         return result;
>     }
> 
>     if (!asMethod(*findResult->value, result)) {
>-        reportProtocolError(BackendDispatcher::InvalidParams, String::format("Parameter '%s' has wrong type. It must be '%s'.", name.utf8().data(), typeName));
>+        reportProtocolError(BackendDispatcher::InvalidParams, makeString("Parameter '", name, "' has wrong type. It must be '", typeName, "'."));
>         return result;
>     }
> 
>diff --git a/Source/JavaScriptCore/inspector/agents/InspectorConsoleAgent.cpp b/Source/JavaScriptCore/inspector/agents/InspectorConsoleAgent.cpp
>index 4cfed7c55f468db4eb1b50f50a824c3fdd7fea99..3fc5e992a950f2019f91648d0d1ae7d2736e42fc 100644
>--- a/Source/JavaScriptCore/inspector/agents/InspectorConsoleAgent.cpp
>+++ b/Source/JavaScriptCore/inspector/agents/InspectorConsoleAgent.cpp
>@@ -35,7 +35,7 @@
> #include "ScriptCallStack.h"
> #include "ScriptCallStackFactory.h"
> #include "ScriptObject.h"
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace Inspector {
> 
>@@ -79,7 +79,7 @@ void InspectorConsoleAgent::enable(ErrorString&)
>     m_enabled = true;
> 
>     if (m_expiredConsoleMessageCount) {
>-        ConsoleMessage expiredMessage(MessageSource::Other, MessageType::Log, MessageLevel::Warning, String::format("%d console messages are not shown.", m_expiredConsoleMessageCount));
>+        ConsoleMessage expiredMessage(MessageSource::Other, MessageType::Log, MessageLevel::Warning, makeString(m_expiredConsoleMessageCount, " console messages are not shown."));
>         expiredMessage.addToFrontend(*m_frontendDispatcher, m_injectedScriptManager, false);
>     }
> 
>diff --git a/Source/JavaScriptCore/jsc.cpp b/Source/JavaScriptCore/jsc.cpp
>index deba637f1213d943b24021f25402cd2fd985a91a..78840132dbf1b68c9fc7f9ad3463e4cfcb9b7eaf 100644
>--- a/Source/JavaScriptCore/jsc.cpp
>+++ b/Source/JavaScriptCore/jsc.cpp
>@@ -91,6 +91,7 @@
> #include <wtf/URL.h>
> #include <wtf/WallTime.h>
> #include <wtf/text/StringBuilder.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> #if OS(WINDOWS)
> #include <direct.h>
>@@ -1172,7 +1173,7 @@ public:
> 
>     StackVisitor::Status operator()(StackVisitor& visitor) const
>     {
>-        m_trace.append(String::format("    %zu   %s\n", visitor->index(), visitor->toString().utf8().data()));
>+        m_trace.append(makeString("    ", visitor->index(), "   ", visitor->toString(), '\n'));
>         return StackVisitor::Continue;
>     }
> 
>diff --git a/Source/JavaScriptCore/runtime/CodeCache.cpp b/Source/JavaScriptCore/runtime/CodeCache.cpp
>index 26e0931d4689d2d9cb401a1c73d16638ae0d9d58..b41e52651f3e7c9f6ecde23ffb9699c89db78657 100644
>--- a/Source/JavaScriptCore/runtime/CodeCache.cpp
>+++ b/Source/JavaScriptCore/runtime/CodeCache.cpp
>@@ -27,6 +27,7 @@
> #include "CodeCache.h"
> 
> #include "IndirectEvalExecutable.h"
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace JSC {
> 
>@@ -196,7 +197,7 @@ void writeCodeBlock(VM& vm, const SourceCodeKey& key, const SourceCodeValue& val
> 
>     std::pair<MallocPtr<uint8_t>, size_t> result = encodeCodeBlock(vm, key, codeBlock);
> 
>-    String filename = makeString(cachePath, '/', String::number(key.hash()), ".cache");
>+    String filename = makeString(cachePath, '/', key.hash(), ".cache");
>     int fd = open(filename.utf8().data(), O_CREAT | O_WRONLY, 0666);
>     if (fd == -1)
>         return;
>diff --git a/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp b/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
>index ae3d680185300d4fb2c2a2207a73a3917de8f34a..1e8d9e3cb3c0261dcd58307358a0497b850463fc 100644
>--- a/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
>+++ b/Source/JavaScriptCore/runtime/IntlDateTimeFormat.cpp
>@@ -504,7 +504,7 @@ void IntlDateTimeFormat::initializeDateTimeFormat(ExecState& exec, JSValue local
>         RETURN_IF_EXCEPTION(scope, void());
>         tz = canonicalizeTimeZoneName(originalTz);
>         if (tz.isNull()) {
>-            throwRangeError(&exec, scope, String::format("invalid time zone: %s", originalTz.utf8().data()));
>+            throwRangeError(&exec, scope, "invalid time zone: " + originalTz);
>             return;
>         }
>     } else
>diff --git a/Source/JavaScriptCore/runtime/IntlObject.cpp b/Source/JavaScriptCore/runtime/IntlObject.cpp
>index 35c0b8822e191c91005c45ede669dcd67754cd75..e17493abf307ec21f948370d0e4514292e57a0d8 100644
>--- a/Source/JavaScriptCore/runtime/IntlObject.cpp
>+++ b/Source/JavaScriptCore/runtime/IntlObject.cpp
>@@ -592,7 +592,7 @@ Vector<String> canonicalizeLocaleList(ExecState& state, JSValue locales)
> 
>             String canonicalizedTag = canonicalizeLanguageTag(tag->value(&state));
>             if (canonicalizedTag.isNull()) {
>-                throwException(&state, scope, createRangeError(&state, String::format("invalid language tag: %s", tag->value(&state).utf8().data())));
>+                throwException(&state, scope, createRangeError(&state, "invalid language tag: " + tag->value(&state)));
>                 return Vector<String>();
>             }
> 
>diff --git a/Source/WTF/wtf/WorkQueue.cpp b/Source/WTF/wtf/WorkQueue.cpp
>index 441b12d34ea881f02bd38f6bd1023025f386e837..288c186280cf47bda290533728e025dd70eb52b3 100644
>--- a/Source/WTF/wtf/WorkQueue.cpp
>+++ b/Source/WTF/wtf/WorkQueue.cpp
>@@ -36,7 +36,7 @@
> #include <wtf/NumberOfCores.h>
> #include <wtf/Ref.h>
> #include <wtf/Threading.h>
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WTF {
> 
>diff --git a/Source/WTF/wtf/dtoa.cpp b/Source/WTF/wtf/dtoa.cpp
>index 84655830e90fb7eb754ec7dd940b253eca5e4e52..683314ffd4e98a5fdc08586fc877881b2ab6cabf 100644
>--- a/Source/WTF/wtf/dtoa.cpp
>+++ b/Source/WTF/wtf/dtoa.cpp
>@@ -1272,7 +1272,7 @@ static inline const char* formatStringTruncatingTrailingZerosIfNeeded(NumberToSt
> 
> const char* numberToFixedPrecisionString(double d, unsigned significantFigures, NumberToStringBuffer buffer, bool truncateTrailingZeros)
> {
>-    // Mimic String::format("%.[precision]g", ...), but use dtoas rounding facilities.
>+    // Mimic sprintf("%.[precision]g", ...), but use dtoas rounding facilities.
>     // "g": Signed value printed in f or e format, whichever is more compact for the given value and precision.
>     // The e format is used only when the exponent of the value is less than â4 or greater than or equal to the
>     // precision argument. Trailing zeros are truncated, and the decimal point appears only if one or more digits follow it.
>@@ -1287,7 +1287,7 @@ const char* numberToFixedPrecisionString(double d, unsigned significantFigures,
> 
> const char* numberToFixedWidthString(double d, unsigned decimalPlaces, NumberToStringBuffer buffer)
> {
>-    // Mimic String::format("%.[precision]f", ...), but use dtoas rounding facilities.
>+    // Mimic sprintf("%.[precision]f", ...), but use dtoas rounding facilities.
>     // "f": Signed value having the form [ â ]dddd.dddd, where dddd is one or more decimal digits.
>     // The number of digits before the decimal point depends on the magnitude of the number, and
>     // the number of digits after the decimal point depends on the requested precision.
>diff --git a/Source/WebCore/Modules/indexeddb/server/SQLiteIDBBackingStore.cpp b/Source/WebCore/Modules/indexeddb/server/SQLiteIDBBackingStore.cpp
>index 285d502dae81a9a768aa34a1d256df5047d61bfd..7415ec818a54a822fb9e380b19d4882903480aea 100644
>--- a/Source/WebCore/Modules/indexeddb/server/SQLiteIDBBackingStore.cpp
>+++ b/Source/WebCore/Modules/indexeddb/server/SQLiteIDBBackingStore.cpp
>@@ -55,6 +55,7 @@
> #include <JavaScriptCore/StructureInlines.h>
> #include <wtf/FileSystem.h>
> #include <wtf/NeverDestroyed.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> using namespace JSC;
>@@ -1844,7 +1845,7 @@ IDBError SQLiteIDBBackingStore::addRecord(const IDBResourceIdentifier& transacti
>         }
> 
>         // We don't already have a file for this blobURL, so commit our file as a unique filename
>-        String storedFilename = String::format("%" PRId64 ".blob", potentialFileNameInteger);
>+        String storedFilename = makeString(potentialFileNameInteger, ".blob");
>         {
>             auto* sql = cachedStatement(SQL::AddBlobFilename, "INSERT INTO BlobFiles VALUES (?, ?);"_s);
>             if (!sql
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBCursorInfo.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBCursorInfo.cpp
>index 0d3e3388f8f272b1dfc3556699a5bd88c9d46431..0e6d9cdeb1fe1b7d7909eec65c53e2836f244356 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBCursorInfo.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBCursorInfo.cpp
>@@ -31,6 +31,7 @@
> #include "IDBDatabase.h"
> #include "IDBTransaction.h"
> #include "IndexedDB.h"
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -100,13 +101,15 @@ IDBCursorInfo IDBCursorInfo::isolatedCopy() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBCursorInfo::loggingString() const
> {
>     if (m_source == IndexedDB::CursorSource::Index)
>-        return String::format("<Crsr: %s Idx %" PRIu64 ", OS %" PRIu64 ", tx %s>", m_cursorIdentifier.loggingString().utf8().data(), m_sourceIdentifier, m_objectStoreIdentifier, m_transactionIdentifier.loggingString().utf8().data());
>+        return makeString("<Crsr: ", m_cursorIdentifier.loggingString(), " Idx ", m_sourceIdentifier, ", OS ", m_objectStoreIdentifier, ", tx ", m_transactionIdentifier.loggingString(), '>');
> 
>-    return String::format("<Crsr: %s OS %" PRIu64 ", tx %s>", m_cursorIdentifier.loggingString().utf8().data(), m_objectStoreIdentifier, m_transactionIdentifier.loggingString().utf8().data());
>+    return makeString("<Crsr: ", m_cursorIdentifier.loggingString(), " OS ", m_objectStoreIdentifier, ", tx ", m_transactionIdentifier.loggingString(), '>');
> }
>+
> #endif
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBGetAllRecordsData.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBGetAllRecordsData.cpp
>index 92b6b923dc8fe92871f7dbbd9e70435032a59d1b..c985d746687f24421ffea1b2d4288df6cd757793 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBGetAllRecordsData.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBGetAllRecordsData.cpp
>@@ -38,12 +38,14 @@ IDBGetAllRecordsData IDBGetAllRecordsData::isolatedCopy() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBGetAllRecordsData::loggingString() const
> {
>     if (indexIdentifier)
>-        return String::format("<GetAllRecords: Idx %" PRIu64 ", OS %" PRIu64 ", %s, range %s>", indexIdentifier, objectStoreIdentifier, getAllType == IndexedDB::GetAllType::Keys ? "Keys" : "Values", keyRangeData.loggingString().utf8().data());
>-    return String::format("<GetAllRecords: OS %" PRIu64 ", %s, range %s>", objectStoreIdentifier, getAllType == IndexedDB::GetAllType::Keys ? "Keys" : "Values", keyRangeData.loggingString().utf8().data());
>+        return makeString("<GetAllRecords: Idx ", indexIdentifier, ", OS ", objectStoreIdentifier, ", ", getAllType == IndexedDB::GetAllType::Keys ? "Keys" : "Values", ", range ", keyRangeData.loggingString(), '>');
>+    return makeString("<GetAllRecords: OS ", objectStoreIdentifier, ", ", getAllType == IndexedDB::GetAllType::Keys ? "Keys" : "Values", ", range ", keyRangeData.loggingString(), '>');
> }
>+
> #endif
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBGetRecordData.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBGetRecordData.cpp
>index d789626047296ed3d18666cde38ddbedad7f8d78..46346dc34929bdccf0260646b0722fe55eec243a 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBGetRecordData.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBGetRecordData.cpp
>@@ -38,10 +38,12 @@ IDBGetRecordData IDBGetRecordData::isolatedCopy() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBGetRecordData::loggingString() const
> {
>-    return String::format("<GetRecord: %s %s>", type == IDBGetRecordDataType::KeyOnly ? "KeyOnly" : "Key+Value", keyRangeData.loggingString().utf8().data());
>+    return makeString("<GetRecord: ", type == IDBGetRecordDataType::KeyOnly ? "KeyOnly" : "Key+Value", ' ', keyRangeData.loggingString(), '>');
> }
>+
> #endif
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBIndexInfo.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBIndexInfo.cpp
>index 27290f4a4a54d8ded9bf4b771e9959789d64abb0..12c5e6f2b5c9c72a62cf20cbe074f944aecd77e2 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBIndexInfo.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBIndexInfo.cpp
>@@ -28,6 +28,8 @@
> 
> #if ENABLE(INDEXED_DATABASE)
> 
>+#include <wtf/text/StringConcatenateNumbers.h>
>+
> namespace WebCore {
> 
> IDBIndexInfo::IDBIndexInfo()
>@@ -50,19 +52,20 @@ IDBIndexInfo IDBIndexInfo::isolatedCopy() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBIndexInfo::loggingString(int indent) const
> {
>     String indentString;
>     for (int i = 0; i < indent; ++i)
>         indentString.append(" ");
>-
>-    return makeString(indentString, "Index: ", m_name, String::format(" (%" PRIu64 ") keyPath: %s\n", m_identifier, WebCore::loggingString(m_keyPath).utf8().data()));
>+    return makeString(indentString, "Index: ", m_name, " (", m_identifier, ") keyPath: ", WebCore::loggingString(m_keyPath), '\n');
> }
> 
> String IDBIndexInfo::condensedLoggingString() const
> {
>-    return String::format("<Idx: %s (%" PRIu64 "), OS (%" PRIu64 ")>", m_name.utf8().data(), m_identifier, m_objectStoreIdentifier);
>+    return makeString("<Idx: ", m_name, " (", m_identifier, "), OS (", m_objectStoreIdentifier, ")>");
> }
>+
> #endif
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBIterateCursorData.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBIterateCursorData.cpp
>index faaeda9febe7404f46473349e01b030f95e79350..593e148d2452830e291f6e65b6bf896d0968022c 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBIterateCursorData.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBIterateCursorData.cpp
>@@ -36,10 +36,12 @@ IDBIterateCursorData IDBIterateCursorData::isolatedCopy() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBIterateCursorData::loggingString() const
> {
>-    return String::format("<Itr8Crsr: key %s, primaryKey %s, count %u>", keyData.loggingString().utf8().data(), primaryKeyData.loggingString().utf8().data(), count);
>+    return makeString("<Itr8Crsr: key ", keyData.loggingString(), ", primaryKey ", primaryKeyData.loggingString(), ", count ", count, '>');
> }
>+
> #endif
> 
> } // namespace WebCore
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBObjectStoreInfo.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBObjectStoreInfo.cpp
>index 04ca90b785f4d2dd00f4f58c9547a57812850a74..2938e9306df1ae3db0643c36fe4532b9baf31e1a 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBObjectStoreInfo.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBObjectStoreInfo.cpp
>@@ -153,7 +153,7 @@ String IDBObjectStoreInfo::loggingString(int indent) const
> 
> String IDBObjectStoreInfo::condensedLoggingString() const
> {
>-    return String::format("<OS: %s (%" PRIu64 ")>", m_name.utf8().data(), m_identifier);
>+    return makeString("<OS: ", m_name, " (", m_identifier, ")>");
> }
> 
> #endif
>diff --git a/Source/WebCore/Modules/indexeddb/shared/IDBResourceIdentifier.cpp b/Source/WebCore/Modules/indexeddb/shared/IDBResourceIdentifier.cpp
>index f673b2dab3d534a59c86adf6d04d7d1b0e5d3486..616d54fadf1edf649c2c562e6b5c585314bf04f6 100644
>--- a/Source/WebCore/Modules/indexeddb/shared/IDBResourceIdentifier.cpp
>+++ b/Source/WebCore/Modules/indexeddb/shared/IDBResourceIdentifier.cpp
>@@ -99,11 +99,14 @@ bool IDBResourceIdentifier::isHashTableDeletedValue() const
> }
> 
> #if !LOG_DISABLED
>+
> String IDBResourceIdentifier::loggingString() const
> {
>-    return String::format("<%" PRIu64", %" PRIu64">", m_idbConnectionIdentifier, m_resourceNumber);
>+    return makeString('<', m_idbConnectionIdentifier, ", ", m_resourceNumber, '>');
> }
>+
> #endif
>+
> } // namespace WebCore
> 
> #endif // ENABLE(INDEXED_DATABASE)
>diff --git a/Source/WebCore/Modules/webdatabase/Database.cpp b/Source/WebCore/Modules/webdatabase/Database.cpp
>index c875f3bf458c9838ffefdf7cf7ac90f9e92dd6a2..7a53fec4998046ae16fb88886bd50ef205c84e6a 100644
>--- a/Source/WebCore/Modules/webdatabase/Database.cpp
>+++ b/Source/WebCore/Modules/webdatabase/Database.cpp
>@@ -107,7 +107,7 @@ static const char* fullyQualifiedInfoTableName()
> 
> static String formatErrorMessage(const char* message, int sqliteErrorCode, const char* sqliteErrorMessage)
> {
>-    return String::format("%s (%d %s)", message, sqliteErrorCode, sqliteErrorMessage);
>+    return makeString(message, " (", sqliteErrorCode, ' ', sqliteErrorMessage, ')');
> }
> 
> static bool setTextValueInDatabase(SQLiteDatabase& db, const String& query, const String& value)
>diff --git a/Source/WebCore/Modules/webdatabase/SQLError.h b/Source/WebCore/Modules/webdatabase/SQLError.h
>index 4e276ca78fc95d759cad30dead07ad6a178e7326..6b072bbb427a89bbff3aa04003a9fe71ed82927a 100644
>--- a/Source/WebCore/Modules/webdatabase/SQLError.h
>+++ b/Source/WebCore/Modules/webdatabase/SQLError.h
>@@ -29,7 +29,7 @@
> #pragma once
> 
> #include <wtf/ThreadSafeRefCounted.h>
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -38,11 +38,11 @@ public:
>     static Ref<SQLError> create(unsigned code, const String& message) { return adoptRef(*new SQLError(code, message)); }
>     static Ref<SQLError> create(unsigned code, const char* message, int sqliteCode)
>     {
>-        return create(code, String::format("%s (%d)", message, sqliteCode));
>+        return create(code, makeString(message, " (", sqliteCode, ')'));
>     }
>     static Ref<SQLError> create(unsigned code, const char* message, int sqliteCode, const char* sqliteMessage)
>     {
>-        return create(code, String::format("%s (%d %s)", message, sqliteCode, sqliteMessage));
>+        return create(code, makeString(message, " (", sqliteCode, ' ', sqliteMessage, ')'));
>     }
> 
>     unsigned code() const { return m_code; }
>diff --git a/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm b/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
>index f92ed2ded991842e233ffedf6c5f57404bac96b6..6af893d53a72e6487236b8e501d198a0313c926d 100644
>--- a/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
>+++ b/Source/WebCore/bindings/scripts/CodeGeneratorJS.pm
>@@ -4572,7 +4572,7 @@ sub GenerateImplementation
>         push(@implContent, "    auto* thisObject = jsCast<${className}*>(cell);\n");
>         push(@implContent, "    builder.setWrappedObjectForCell(cell, &thisObject->wrapped());\n");
>         push(@implContent, "    if (thisObject->scriptExecutionContext())\n");
>-        push(@implContent, "        builder.setLabelForCell(cell, String::format(\"url %s\", thisObject->scriptExecutionContext()->url().string().utf8().data()));\n");
>+        push(@implContent, "        builder.setLabelForCell(cell, \"url \" + thisObject->scriptExecutionContext()->url().string());\n");
>         push(@implContent, "    Base::heapSnapshot(cell, builder);\n");
>         push(@implContent, "}\n\n");
>     }
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSInterfaceName.cpp b/Source/WebCore/bindings/scripts/test/JS/JSInterfaceName.cpp
>index 6d9bd17b6d154e0bf0a6ff8b01b001d3356dfe6e..141eb8ee56904cf3772d96be6fb34e4782340fb1 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSInterfaceName.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSInterfaceName.cpp
>@@ -176,7 +176,7 @@ void JSInterfaceName::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSInterfaceName*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSMapLike.cpp b/Source/WebCore/bindings/scripts/test/JS/JSMapLike.cpp
>index 079c666294aeeca8274ae2bce5efe4ea77b16b4d..3567a72d07fd6c7ae1e48cb3b348849f208853df 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSMapLike.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSMapLike.cpp
>@@ -345,7 +345,7 @@ void JSMapLike::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSMapLike*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSReadOnlyMapLike.cpp b/Source/WebCore/bindings/scripts/test/JS/JSReadOnlyMapLike.cpp
>index 97d4f3ab4fa1602ae490ae86c96e0c38478bf934..ab281f059d6b317c2c9233d0c6809a1ff796cd30 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSReadOnlyMapLike.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSReadOnlyMapLike.cpp
>@@ -294,7 +294,7 @@ void JSReadOnlyMapLike::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSReadOnlyMapLike*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestActiveDOMObject.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestActiveDOMObject.cpp
>index 6cc23ad0131d112f22da8d8adf1205bbb1adb157..2b614176fc0809a85a4f0b69c7dbfdc9e9ac2bcd 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestActiveDOMObject.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestActiveDOMObject.cpp
>@@ -255,7 +255,7 @@ void JSTestActiveDOMObject::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& buil
>     auto* thisObject = jsCast<JSTestActiveDOMObject*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactions.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactions.cpp
>index 4a027936b9db99360bfdd78a97b6b35d64686cae..a1bdab10f5ea296880fa08822dadce3d1c08e6ac 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactions.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactions.cpp
>@@ -435,7 +435,7 @@ void JSTestCEReactions::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestCEReactions*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactionsStringifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactionsStringifier.cpp
>index 342a0df8d1e2835284bc36be61dbbbf27bb28d0c..580e2437393c5e0f89c9a2752e743ec894668128 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactionsStringifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestCEReactionsStringifier.cpp
>@@ -264,7 +264,7 @@ void JSTestCEReactionsStringifier::heapSnapshot(JSCell* cell, HeapSnapshotBuilde
>     auto* thisObject = jsCast<JSTestCEReactionsStringifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestCallTracer.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestCallTracer.cpp
>index 2e8de514bc437ec6b634b5c5220ff523355d0cc3..6b81bffe495e500bcba3451c7fd7b6bee7754250 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestCallTracer.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestCallTracer.cpp
>@@ -528,7 +528,7 @@ void JSTestCallTracer::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestCallTracer*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestClassWithJSBuiltinConstructor.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestClassWithJSBuiltinConstructor.cpp
>index 008b5e89768695f25c833ba34601d4be57d0e248..5c8c78558c59a2b1b2368b0bb6143c06d1ce0a3e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestClassWithJSBuiltinConstructor.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestClassWithJSBuiltinConstructor.cpp
>@@ -168,7 +168,7 @@ void JSTestClassWithJSBuiltinConstructor::heapSnapshot(JSCell* cell, HeapSnapsho
>     auto* thisObject = jsCast<JSTestClassWithJSBuiltinConstructor*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestDOMJIT.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestDOMJIT.cpp
>index 95d767047388e38c01004295d8cf13456bd44bde..83b0f7d9e4b5394c1dd40344a466e53d033dbee6 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestDOMJIT.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestDOMJIT.cpp
>@@ -1266,7 +1266,7 @@ void JSTestDOMJIT::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestDOMJIT*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestEnabledBySetting.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestEnabledBySetting.cpp
>index 660b9775bcfd4a21515f80c2fbe556498b8d6be3..4df8130ff5f822d241eca49aa8a9d8348109642a 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestEnabledBySetting.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestEnabledBySetting.cpp
>@@ -307,7 +307,7 @@ void JSTestEnabledBySetting::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& bui
>     auto* thisObject = jsCast<JSTestEnabledBySetting*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestEventConstructor.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestEventConstructor.cpp
>index 45dc1927049be2720552a98b7df235b0f5a15bd0..33e2f9d4a0fc381f966ab9fb8b1c9e7092f286c8 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestEventConstructor.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestEventConstructor.cpp
>@@ -311,7 +311,7 @@ void JSTestEventConstructor::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& bui
>     auto* thisObject = jsCast<JSTestEventConstructor*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestEventTarget.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestEventTarget.cpp
>index 0ec06408fefb3aedb5dcbc12281fd1db0c9385d1..5fc7cb6c555e745bcfbabca0643118c6d61f076f 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestEventTarget.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestEventTarget.cpp
>@@ -254,7 +254,7 @@ void JSTestEventTarget::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestEventTarget*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestException.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestException.cpp
>index d32c04cc50eedf269ed801d69123f6b505404721..36d62411a8d99e133e75ae2bb1200b993d5d0a14 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestException.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestException.cpp
>@@ -185,7 +185,7 @@ void JSTestException::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestException*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestGenerateIsReachable.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestGenerateIsReachable.cpp
>index b0d9d49fc92683f5e1d6fb8fd685df5d33b24be8..9f16b828c8b3d2e953e3558ea7f2e0583f293379 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestGenerateIsReachable.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestGenerateIsReachable.cpp
>@@ -194,7 +194,7 @@ void JSTestGenerateIsReachable::heapSnapshot(JSCell* cell, HeapSnapshotBuilder&
>     auto* thisObject = jsCast<JSTestGenerateIsReachable*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestGlobalObject.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestGlobalObject.cpp
>index b20b83c7be9e5b37b9cc5758663e1785585e392c..cec371f68d4dc7dc9936733f47b559fa7f4f9157 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestGlobalObject.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestGlobalObject.cpp
>@@ -614,7 +614,7 @@ void JSTestGlobalObject::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder
>     auto* thisObject = jsCast<JSTestGlobalObject*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterNoIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterNoIdentifier.cpp
>index 57892537be878324a5dde8f6d1c592c1b962b725..093adcba6e45698eb4d6ba295b49340ec1feab55 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterNoIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterNoIdentifier.cpp
>@@ -253,7 +253,7 @@ void JSTestIndexedSetterNoIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBui
>     auto* thisObject = jsCast<JSTestIndexedSetterNoIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterThrowingException.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterThrowingException.cpp
>index 355adcd90aefcf595d07ed546e4caab20b3ee244..615802d96e77ecf61e6e67972d7b6ff96ec7793e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterThrowingException.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterThrowingException.cpp
>@@ -253,7 +253,7 @@ void JSTestIndexedSetterThrowingException::heapSnapshot(JSCell* cell, HeapSnapsh
>     auto* thisObject = jsCast<JSTestIndexedSetterThrowingException*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterWithIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterWithIdentifier.cpp
>index 769673afbb4e6201d94c32a84cf249ee60388fe6..a871231879a9f0b64dd5ca995b401655024ae400 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterWithIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestIndexedSetterWithIdentifier.cpp
>@@ -285,7 +285,7 @@ void JSTestIndexedSetterWithIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotB
>     auto* thisObject = jsCast<JSTestIndexedSetterWithIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestInterface.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestInterface.cpp
>index 6ea3f9745b2ab48276c51ae3deaa4c1d5808a269..d6c41fb10c356d56d0ef9a7281e98b745cf0ee16 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestInterface.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestInterface.cpp
>@@ -1022,7 +1022,7 @@ void JSTestInterface::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestInterface*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestInterfaceLeadingUnderscore.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestInterfaceLeadingUnderscore.cpp
>index cff32ff0eb3adda77fe9463a2a4f99ce658b4970..c94182c2444473dd7c57aabaf30b5108a96fcb00 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestInterfaceLeadingUnderscore.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestInterfaceLeadingUnderscore.cpp
>@@ -185,7 +185,7 @@ void JSTestInterfaceLeadingUnderscore::heapSnapshot(JSCell* cell, HeapSnapshotBu
>     auto* thisObject = jsCast<JSTestInterfaceLeadingUnderscore*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestIterable.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestIterable.cpp
>index ac1e8e7f9ef829278e245845a66231a5fcbcab08..1a9237470c8fd6581bf046a040a1e6ea7c177a4c 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestIterable.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestIterable.cpp
>@@ -238,7 +238,7 @@ void JSTestIterable::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestIterable*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestMediaQueryListListener.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestMediaQueryListListener.cpp
>index 00faf9f0573fd0075de8de5149e8eb50874c94fc..fa78d03cc5bc7cd9717934fb0268f7f467d590f7 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestMediaQueryListListener.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestMediaQueryListListener.cpp
>@@ -194,7 +194,7 @@ void JSTestMediaQueryListListener::heapSnapshot(JSCell* cell, HeapSnapshotBuilde
>     auto* thisObject = jsCast<JSTestMediaQueryListListener*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterNoIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterNoIdentifier.cpp
>index 953120729560a53298c63063ba9ac2094633c266..35b77a74db67869f4da76726848ca3c633950c57 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterNoIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterNoIdentifier.cpp
>@@ -319,7 +319,7 @@ void JSTestNamedAndIndexedSetterNoIdentifier::heapSnapshot(JSCell* cell, HeapSna
>     auto* thisObject = jsCast<JSTestNamedAndIndexedSetterNoIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterThrowingException.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterThrowingException.cpp
>index 05954622f06db43454d3bbed2e0621a9316126e1..f1b1da1b54b4ba24c8794e921db565b991c9dc7f 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterThrowingException.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterThrowingException.cpp
>@@ -319,7 +319,7 @@ void JSTestNamedAndIndexedSetterThrowingException::heapSnapshot(JSCell* cell, He
>     auto* thisObject = jsCast<JSTestNamedAndIndexedSetterThrowingException*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterWithIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterWithIdentifier.cpp
>index 55b5af318a7c0d67ef6bc7508e446766991d7561..fb6089cbd41a5bfe3282737b227158d30817fe7a 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterWithIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedAndIndexedSetterWithIdentifier.cpp
>@@ -373,7 +373,7 @@ void JSTestNamedAndIndexedSetterWithIdentifier::heapSnapshot(JSCell* cell, HeapS
>     auto* thisObject = jsCast<JSTestNamedAndIndexedSetterWithIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedConstructor.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedConstructor.cpp
>index f1a84a8bad9a5d605a10e49d9c5c4273d99287e1..022d3cdc3fe940c24eca85ab3bf8b184e06e78ef 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedConstructor.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedConstructor.cpp
>@@ -205,7 +205,7 @@ void JSTestNamedConstructor::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& bui
>     auto* thisObject = jsCast<JSTestNamedConstructor*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterNoIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterNoIdentifier.cpp
>index 97d826a5910fad8088bf6557e9af7150ddb21ca2..e7d91f8c868c253d6b88012142553112c3f8d80e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterNoIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterNoIdentifier.cpp
>@@ -233,7 +233,7 @@ void JSTestNamedDeleterNoIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBuil
>     auto* thisObject = jsCast<JSTestNamedDeleterNoIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterThrowingException.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterThrowingException.cpp
>index d1ef306b6a9cd0ff8268b0c767abf8f47bb7070f..a7d76ba7a3deb5845304be65c89d8e0da29daf7a 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterThrowingException.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterThrowingException.cpp
>@@ -247,7 +247,7 @@ void JSTestNamedDeleterThrowingException::heapSnapshot(JSCell* cell, HeapSnapsho
>     auto* thisObject = jsCast<JSTestNamedDeleterThrowingException*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIdentifier.cpp
>index e4fa39130a3964d343cbef3df0c0f8c7a2e5940f..9edab591d948349650ad123919f6b36316d54d6b 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIdentifier.cpp
>@@ -264,7 +264,7 @@ void JSTestNamedDeleterWithIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBu
>     auto* thisObject = jsCast<JSTestNamedDeleterWithIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIndexedGetter.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIndexedGetter.cpp
>index cf4640b2365ce48dfa140618e8f2a7296efbad32..2fb624a015b4ba7898d909250bd074c920ca6e3e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIndexedGetter.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedDeleterWithIndexedGetter.cpp
>@@ -250,7 +250,7 @@ void JSTestNamedDeleterWithIndexedGetter::heapSnapshot(JSCell* cell, HeapSnapsho
>     auto* thisObject = jsCast<JSTestNamedDeleterWithIndexedGetter*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterCallWith.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterCallWith.cpp
>index 41a6283e34ef32a5340a28ef92b46468ebc14bb7..f5959690980573180e86246f1483be9d03090f2e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterCallWith.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterCallWith.cpp
>@@ -212,7 +212,7 @@ void JSTestNamedGetterCallWith::heapSnapshot(JSCell* cell, HeapSnapshotBuilder&
>     auto* thisObject = jsCast<JSTestNamedGetterCallWith*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterNoIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterNoIdentifier.cpp
>index 249fc8dc86b079854a9e97d35fa50736cd621596..fae104a834cd1db8a4b2a41a7c167c9b7bd1f8a5 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterNoIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterNoIdentifier.cpp
>@@ -212,7 +212,7 @@ void JSTestNamedGetterNoIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBuild
>     auto* thisObject = jsCast<JSTestNamedGetterNoIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterWithIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterWithIdentifier.cpp
>index ea02a42eef4d7f387dbcf969c44004b57fc307af..918b2d61ebd6d22f7062164f65dd241ca48b4814 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterWithIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedGetterWithIdentifier.cpp
>@@ -240,7 +240,7 @@ void JSTestNamedGetterWithIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBui
>     auto* thisObject = jsCast<JSTestNamedGetterWithIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterNoIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterNoIdentifier.cpp
>index f431ade3197ef9ee98181900316b80526972e369..021ce1ea16742d3910eab1e9756e1655fbf757b1 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterNoIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterNoIdentifier.cpp
>@@ -274,7 +274,7 @@ void JSTestNamedSetterNoIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBuild
>     auto* thisObject = jsCast<JSTestNamedSetterNoIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterThrowingException.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterThrowingException.cpp
>index 64437fcfdeb29e662f3d7c69068f6b11d28536bf..052a1a22825ab4d6099b8db6da18d5174d50ba01 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterThrowingException.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterThrowingException.cpp
>@@ -274,7 +274,7 @@ void JSTestNamedSetterThrowingException::heapSnapshot(JSCell* cell, HeapSnapshot
>     auto* thisObject = jsCast<JSTestNamedSetterThrowingException*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIdentifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIdentifier.cpp
>index e82d799d1af12482e01d507c0fce0190d4da1d6b..0b8f5de1cac641abdf0f690bd82dbb05d3f29a71 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIdentifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIdentifier.cpp
>@@ -305,7 +305,7 @@ void JSTestNamedSetterWithIdentifier::heapSnapshot(JSCell* cell, HeapSnapshotBui
>     auto* thisObject = jsCast<JSTestNamedSetterWithIdentifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetter.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetter.cpp
>index 65e3ed02e20be33f3b77ccbde4d365ccbe3604c3..090da163fc52093171cb4fdc04abd6beb8577850 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetter.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetter.cpp
>@@ -347,7 +347,7 @@ void JSTestNamedSetterWithIndexedGetter::heapSnapshot(JSCell* cell, HeapSnapshot
>     auto* thisObject = jsCast<JSTestNamedSetterWithIndexedGetter*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetterAndSetter.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetterAndSetter.cpp
>index a69d0d74bbb6c1769c4a8046aae17d1e4a3c6b8a..5d0ba23c476c9c6215b2ce7e115f3559839caf2c 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetterAndSetter.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithIndexedGetterAndSetter.cpp
>@@ -397,7 +397,7 @@ void JSTestNamedSetterWithIndexedGetterAndSetter::heapSnapshot(JSCell* cell, Hea
>     auto* thisObject = jsCast<JSTestNamedSetterWithIndexedGetterAndSetter*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithOverrideBuiltins.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithOverrideBuiltins.cpp
>index 1d84e78489918d77d8130d69cd3ac0d57ce636ac..f27629c7bbb3a2b88bb556d09e754536eb7c400e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithOverrideBuiltins.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithOverrideBuiltins.cpp
>@@ -261,7 +261,7 @@ void JSTestNamedSetterWithOverrideBuiltins::heapSnapshot(JSCell* cell, HeapSnaps
>     auto* thisObject = jsCast<JSTestNamedSetterWithOverrideBuiltins*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgableProperties.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgableProperties.cpp
>index d0e854eea667edf906caaf5f3e3855e221e49bbc..d4d9738cdb01b8426b663c21fc8298f144ba2637 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgableProperties.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgableProperties.cpp
>@@ -343,7 +343,7 @@ void JSTestNamedSetterWithUnforgableProperties::heapSnapshot(JSCell* cell, HeapS
>     auto* thisObject = jsCast<JSTestNamedSetterWithUnforgableProperties*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins.cpp
>index cbdbaa28f73dd0f61e66b839fd4f182c9b226e85..ce59e749c273e01c4409f6653af5dfa8d04d2a34 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins.cpp
>@@ -330,7 +330,7 @@ void JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins::heapSnapshot(
>     auto* thisObject = jsCast<JSTestNamedSetterWithUnforgablePropertiesAndOverrideBuiltins*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
>index 35a2d623f89cf042eb02b55c56e8995930eee232..264bf961423acb7819bcebdc904f2730e88a8c1c 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestNode.cpp
>@@ -429,7 +429,7 @@ void JSTestNode::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestNode*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
>index 21c10c7cfaa36db715c2359caf3ba276274d06c5..eae2f29e5fb5c8fc6f38bfbb2050055c6ef7c344 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestObj.cpp
>@@ -8546,7 +8546,7 @@ void JSTestObj::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestObj*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructors.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructors.cpp
>index 1adb70212f451cce85b08cda036fe478089c3978..7708eda3aadc73bd12ff15ed68e3188629714801 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructors.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructors.cpp
>@@ -257,7 +257,7 @@ void JSTestOverloadedConstructors::heapSnapshot(JSCell* cell, HeapSnapshotBuilde
>     auto* thisObject = jsCast<JSTestOverloadedConstructors*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructorsWithSequence.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructorsWithSequence.cpp
>index b055668596bc6f27c82c716fd234e5d80aa8a4c5..3831269640733ec635b7ecc46c833b73f550ac17 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructorsWithSequence.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestOverloadedConstructorsWithSequence.cpp
>@@ -213,7 +213,7 @@ void JSTestOverloadedConstructorsWithSequence::heapSnapshot(JSCell* cell, HeapSn
>     auto* thisObject = jsCast<JSTestOverloadedConstructorsWithSequence*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestOverrideBuiltins.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestOverrideBuiltins.cpp
>index 6c6c044efc5f1c71ea713c212b03952f6f94444a..9b5a0272316c7583af327c2bae97f52c79cc8399 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestOverrideBuiltins.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestOverrideBuiltins.cpp
>@@ -243,7 +243,7 @@ void JSTestOverrideBuiltins::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& bui
>     auto* thisObject = jsCast<JSTestOverrideBuiltins*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestPluginInterface.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestPluginInterface.cpp
>index bec57d5517d5b09c8d20a0ade4297cf0ae8dfced..c340edd757895eecb11b6ffc321d588c522472a2 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestPluginInterface.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestPluginInterface.cpp
>@@ -216,7 +216,7 @@ void JSTestPluginInterface::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& buil
>     auto* thisObject = jsCast<JSTestPluginInterface*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestPromiseRejectionEvent.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestPromiseRejectionEvent.cpp
>index 7a258986714630a3053bc7481a5de0fef1bd798f..c8da5dd06c8b14d5880fd1fceec94af600e0cd9d 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestPromiseRejectionEvent.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestPromiseRejectionEvent.cpp
>@@ -293,7 +293,7 @@ void JSTestPromiseRejectionEvent::heapSnapshot(JSCell* cell, HeapSnapshotBuilder
>     auto* thisObject = jsCast<JSTestPromiseRejectionEvent*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestSerialization.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestSerialization.cpp
>index 78d1c41c428c01e1f75f6e91a64aeb305c0a525f..eaf57f8a81372e01c3ff195abd524b7294d1709d 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestSerialization.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestSerialization.cpp
>@@ -550,7 +550,7 @@ void JSTestSerialization::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builde
>     auto* thisObject = jsCast<JSTestSerialization*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationIndirectInheritance.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationIndirectInheritance.cpp
>index 133eda02e640163fc9be65434820fb925f04c0a4..64920052284ae525b12c6e720d83de17f4ece6d3 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationIndirectInheritance.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationIndirectInheritance.cpp
>@@ -154,7 +154,7 @@ void JSTestSerializationIndirectInheritance::heapSnapshot(JSCell* cell, HeapSnap
>     auto* thisObject = jsCast<JSTestSerializationIndirectInheritance*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInherit.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInherit.cpp
>index ad531b20b74bc6d259569182eaefc5311cf8e092..4442f5139bec98be4b11a6b0d83c7348a8c44382 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInherit.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInherit.cpp
>@@ -229,7 +229,7 @@ void JSTestSerializationInherit::heapSnapshot(JSCell* cell, HeapSnapshotBuilder&
>     auto* thisObject = jsCast<JSTestSerializationInherit*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInheritFinal.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInheritFinal.cpp
>index a1ac2d010e51c4837c0f0b546228034ad0db84e8..ba61bc52a84f70fd34301c38f73f970d4c9f0f4e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInheritFinal.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializationInheritFinal.cpp
>@@ -263,7 +263,7 @@ void JSTestSerializationInheritFinal::heapSnapshot(JSCell* cell, HeapSnapshotBui
>     auto* thisObject = jsCast<JSTestSerializationInheritFinal*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializedScriptValueInterface.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializedScriptValueInterface.cpp
>index df7dfb8f961d94fe8e24f01d241fb24f6a94faef..42b2836f9d2e791735945484643dca28f567ed5b 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestSerializedScriptValueInterface.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestSerializedScriptValueInterface.cpp
>@@ -353,7 +353,7 @@ void JSTestSerializedScriptValueInterface::heapSnapshot(JSCell* cell, HeapSnapsh
>     auto* thisObject = jsCast<JSTestSerializedScriptValueInterface*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifier.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifier.cpp
>index 5242bb8baac6fc8ca1404060f150bb1dd7c015df..31392cb920b79fbbcb34edd29e14784eee2a36ae 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifier.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifier.cpp
>@@ -187,7 +187,7 @@ void JSTestStringifier::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestStringifier*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierAnonymousOperation.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierAnonymousOperation.cpp
>index 7cae2439ef627b6c26617394b91cc8b804ff055b..58cd0ff94092bce04c291fff32b0d6dae39d1bc2 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierAnonymousOperation.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierAnonymousOperation.cpp
>@@ -187,7 +187,7 @@ void JSTestStringifierAnonymousOperation::heapSnapshot(JSCell* cell, HeapSnapsho
>     auto* thisObject = jsCast<JSTestStringifierAnonymousOperation*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierNamedOperation.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierNamedOperation.cpp
>index 50a46f614f9848b769285e16389073c129157fd1..c9b25f0ad9d6bb83e760e42ac9411abae1ce9b6e 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierNamedOperation.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierNamedOperation.cpp
>@@ -202,7 +202,7 @@ void JSTestStringifierNamedOperation::heapSnapshot(JSCell* cell, HeapSnapshotBui
>     auto* thisObject = jsCast<JSTestStringifierNamedOperation*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationImplementedAs.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationImplementedAs.cpp
>index 0a33af378a2b1219f29284dc89e16d38b724779d..35d863a85d62497480b1a5f84549bae4efd1f198 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationImplementedAs.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationImplementedAs.cpp
>@@ -202,7 +202,7 @@ void JSTestStringifierOperationImplementedAs::heapSnapshot(JSCell* cell, HeapSna
>     auto* thisObject = jsCast<JSTestStringifierOperationImplementedAs*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationNamedToString.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationNamedToString.cpp
>index 49049174e036f5f1806244c3f2ebd19e16962e44..6ba4cd1fd05810ea79d81fc8af0bb8c64c6261b9 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationNamedToString.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierOperationNamedToString.cpp
>@@ -187,7 +187,7 @@ void JSTestStringifierOperationNamedToString::heapSnapshot(JSCell* cell, HeapSna
>     auto* thisObject = jsCast<JSTestStringifierOperationNamedToString*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadOnlyAttribute.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadOnlyAttribute.cpp
>index c9c52698b82d3fff27d2344fddb5543d092ca406..41523a5af2ac1e869a9ad10d384ef4d4d07848c3 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadOnlyAttribute.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadOnlyAttribute.cpp
>@@ -209,7 +209,7 @@ void JSTestStringifierReadOnlyAttribute::heapSnapshot(JSCell* cell, HeapSnapshot
>     auto* thisObject = jsCast<JSTestStringifierReadOnlyAttribute*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadWriteAttribute.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadWriteAttribute.cpp
>index 75ec38adb8fe8893046035346b56446d7b2b62f4..7cc60e80c8e32111647773a6c004359334f48d3c 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadWriteAttribute.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestStringifierReadWriteAttribute.cpp
>@@ -227,7 +227,7 @@ void JSTestStringifierReadWriteAttribute::heapSnapshot(JSCell* cell, HeapSnapsho
>     auto* thisObject = jsCast<JSTestStringifierReadWriteAttribute*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/bindings/scripts/test/JS/JSTestTypedefs.cpp b/Source/WebCore/bindings/scripts/test/JS/JSTestTypedefs.cpp
>index 0eb867e541b197223b95a563b43731e3eb7b1718..906b66de8fa22cd2735eb9b36f9ffee80a283b65 100644
>--- a/Source/WebCore/bindings/scripts/test/JS/JSTestTypedefs.cpp
>+++ b/Source/WebCore/bindings/scripts/test/JS/JSTestTypedefs.cpp
>@@ -749,7 +749,7 @@ void JSTestTypedefs::heapSnapshot(JSCell* cell, HeapSnapshotBuilder& builder)
>     auto* thisObject = jsCast<JSTestTypedefs*>(cell);
>     builder.setWrappedObjectForCell(cell, &thisObject->wrapped());
>     if (thisObject->scriptExecutionContext())
>-        builder.setLabelForCell(cell, String::format("url %s", thisObject->scriptExecutionContext()->url().string().utf8().data()));
>+        builder.setLabelForCell(cell, "url " + thisObject->scriptExecutionContext()->url().string());
>     Base::heapSnapshot(cell, builder);
> }
> 
>diff --git a/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp b/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
>index e6dbed7ab27fc93a25bd03dfa9e3b8e96a13a437..a52b1958b3fe95edad8a58ae2d56889c679bd269 100644
>--- a/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
>+++ b/Source/WebCore/css/parser/CSSPropertyParserHelpers.cpp
>@@ -43,6 +43,7 @@
> #include "CSSValuePool.h"
> #include "Pair.h"
> #include "StyleColor.h"
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -721,9 +722,9 @@ static Color parseHexColor(CSSParserTokenRange& range, bool acceptQuirkyColors)
>                 || token.numericValue() < 0. || token.numericValue() >= 1000000.)
>                 return Color();
>             if (token.type() == NumberToken) // e.g. 112233
>-                color = String::format("%d", static_cast<int>(token.numericValue()));
>+                color = String::number(static_cast<int>(token.numericValue()));
>             else // e.g. 0001FF
>-                color = String::number(static_cast<int>(token.numericValue())) + token.value().toString();
>+                color = makeString(static_cast<int>(token.numericValue()), token.value().toString());
>             while (color.length() < 6)
>                 color = "0" + color;
>         } else if (token.type() == IdentToken) { // e.g. FF0000
>diff --git a/Source/WebCore/html/HTMLSelectElement.cpp b/Source/WebCore/html/HTMLSelectElement.cpp
>index 5de320e828ecd7eb0c39c535a59b4528ee70abfa..d499b91b80d014353b8f36ab1f08f7bb53dffd39 100644
>--- a/Source/WebCore/html/HTMLSelectElement.cpp
>+++ b/Source/WebCore/html/HTMLSelectElement.cpp
>@@ -55,6 +55,7 @@
> #include "Settings.h"
> #include "SpatialNavigation.h"
> #include <wtf/IsoMallocInlines.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -458,7 +459,7 @@ ExceptionOr<void> HTMLSelectElement::setItem(unsigned index, HTMLOptionElement*
> ExceptionOr<void> HTMLSelectElement::setLength(unsigned newLength)
> {
>     if (newLength > length() && newLength > maxSelectItems) {
>-        document().addConsoleMessage(MessageSource::Other, MessageLevel::Warning, String::format("Blocked attempt to expand the option list to %u items. The maximum number of items allowed is %u.", newLength, maxSelectItems));
>+        document().addConsoleMessage(MessageSource::Other, MessageLevel::Warning, makeString("Blocked attempt to expand the option list to ", newLength, " items. The maximum number of items allowed is ", maxSelectItems, '.'));
>         return { };
>     }
> 
>diff --git a/Source/WebCore/html/ImageDocument.cpp b/Source/WebCore/html/ImageDocument.cpp
>index 8ecca709c10d1d3637fbd53ec3990bdc87be26af..f4292232e9dc22d729ab5950896ab8688380a2f8 100644
>--- a/Source/WebCore/html/ImageDocument.cpp
>+++ b/Source/WebCore/html/ImageDocument.cpp
>@@ -49,6 +49,7 @@
> #include "RenderElement.h"
> #include "Settings.h"
> #include <wtf/IsoMallocInlines.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -273,7 +274,7 @@ void ImageDocument::imageUpdated()
> #if PLATFORM(IOS_FAMILY)
>         FloatSize screenSize = page()->chrome().screenSize();
>         if (imageSize.width() > screenSize.width())
>-            processViewport(String::format("width=%u,viewport-fit=cover", static_cast<unsigned>(imageSize.width().toInt())), ViewportArguments::ImageDocument);
>+            processViewport(makeString("width=", imageSize.width().toInt(), ",viewport-fit=cover"), ViewportArguments::ImageDocument);
> 
>         if (page())
>             page()->chrome().client().imageOrMediaDocumentSizeChanged(IntSize(imageSize.width(), imageSize.height()));
>diff --git a/Source/WebCore/html/parser/XSSAuditor.cpp b/Source/WebCore/html/parser/XSSAuditor.cpp
>index 5eedb440d2945e3d1a4e1212bc9c29baaf9cdbb6..da9c333f5479657035f74eadb2d3d50f61aa583d 100644
>--- a/Source/WebCore/html/parser/XSSAuditor.cpp
>+++ b/Source/WebCore/html/parser/XSSAuditor.cpp
>@@ -45,7 +45,7 @@
> #include <wtf/ASCIICType.h>
> #include <wtf/MainThread.h>
> #include <wtf/NeverDestroyed.h>
>-#include <wtf/text/StringView.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -332,7 +332,7 @@ void XSSAuditor::init(Document* document, XSSAuditorDelegate* auditorDelegate)
>             }
>         }
>         if (m_xssProtection == XSSProtectionDisposition::Invalid) {
>-            document->addConsoleMessage(MessageSource::Security, MessageLevel::Error, "Error parsing header X-XSS-Protection: " + headerValue + ": "  + errorDetails + " at character position " + String::format("%u", errorPosition) + ". The default protections will be applied.");
>+            document->addConsoleMessage(MessageSource::Security, MessageLevel::Error, makeString("Error parsing header X-XSS-Protection: ", headerValue, ": ", errorDetails, " at character position ", errorPosition, ". The default protections will be applied."));
>             m_xssProtection = XSSProtectionDisposition::Enabled;
>         }
> 
>diff --git a/Source/WebCore/inspector/InspectorFrontendClientLocal.cpp b/Source/WebCore/inspector/InspectorFrontendClientLocal.cpp
>index a0c3887a6efc2a051c3a353147d7136cf8ac8ab4..243d849c9bf1a1e59d8fa74874892b2652226e03 100644
>--- a/Source/WebCore/inspector/InspectorFrontendClientLocal.cpp
>+++ b/Source/WebCore/inspector/InspectorFrontendClientLocal.cpp
>@@ -205,7 +205,7 @@ bool InspectorFrontendClientLocal::canAttachWindow()
> 
> void InspectorFrontendClientLocal::setDockingUnavailable(bool unavailable)
> {
>-    evaluateOnLoad(String::format("[\"setDockingUnavailable\", %s]", unavailable ? "true" : "false"));
>+    evaluateOnLoad(makeString("[\"setDockingUnavailable\", ", unavailable ? "true" : "false", ']'));
> }
> 
> void InspectorFrontendClientLocal::changeAttachedWindowHeight(unsigned height)
>@@ -270,7 +270,7 @@ void InspectorFrontendClientLocal::setAttachedWindow(DockSide dockSide)
> 
>     m_dockSide = dockSide;
> 
>-    evaluateOnLoad(String::format("[\"setDockSide\", \"%s\"]", side));
>+    evaluateOnLoad(makeString("[\"setDockSide\", \"", side, "\"]"));
> }
> 
> void InspectorFrontendClientLocal::restoreAttachedWindowHeight()
>@@ -294,7 +294,7 @@ bool InspectorFrontendClientLocal::isDebuggingEnabled()
> 
> void InspectorFrontendClientLocal::setDebuggingEnabled(bool enabled)
> {
>-    evaluateOnLoad(String::format("[\"setDebuggingEnabled\", %s]", enabled ? "true" : "false"));
>+    evaluateOnLoad(makeString("[\"setDebuggingEnabled\", ", enabled ? "true" : "false", ']'));
> }
> 
> bool InspectorFrontendClientLocal::isTimelineProfilingEnabled()
>@@ -306,7 +306,7 @@ bool InspectorFrontendClientLocal::isTimelineProfilingEnabled()
> 
> void InspectorFrontendClientLocal::setTimelineProfilingEnabled(bool enabled)
> {
>-    evaluateOnLoad(String::format("[\"setTimelineProfilingEnabled\", %s]", enabled ? "true" : "false"));
>+    evaluateOnLoad(makeString("[\"setTimelineProfilingEnabled\", ", enabled ? "true" : "false", ']'));
> }
> 
> bool InspectorFrontendClientLocal::isProfilingJavaScript()
>@@ -339,7 +339,7 @@ void InspectorFrontendClientLocal::showResources()
> void InspectorFrontendClientLocal::showMainResourceForFrame(Frame* frame)
> {
>     String frameId = m_inspectedPageController->pageAgent()->frameId(frame);
>-    evaluateOnLoad(String::format("[\"showMainResourceForFrame\", \"%s\"]", frameId.ascii().data()));
>+    evaluateOnLoad(makeString("[\"showMainResourceForFrame\", \"", frameId, "\"]"));
> }
> 
> unsigned InspectorFrontendClientLocal::constrainedAttachedWindowHeight(unsigned preferredHeight, unsigned totalWindowHeight)
>diff --git a/Source/WebCore/inspector/agents/InspectorCSSAgent.cpp b/Source/WebCore/inspector/agents/InspectorCSSAgent.cpp
>index 4577652579af56497c52beb2d9dc125b45ed54d8..d5a22741339d524092988cad87015a717611aeb2 100644
>--- a/Source/WebCore/inspector/agents/InspectorCSSAgent.cpp
>+++ b/Source/WebCore/inspector/agents/InspectorCSSAgent.cpp
>@@ -62,8 +62,7 @@
> #include <wtf/Ref.h>
> #include <wtf/Vector.h>
> #include <wtf/text/CString.h>
>-#include <wtf/text/StringConcatenate.h>
>-
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -157,7 +156,7 @@ private:
> 
>     String mergeId() final
>     {
>-        return String::format("SetStyleSheetText %s", m_styleSheet->id().utf8().data());
>+        return "SetStyleSheetText " + m_styleSheet->id();
>     }
> 
>     void merge(std::unique_ptr<Action> action) override
>@@ -198,7 +197,7 @@ public:
>     String mergeId() override
>     {
>         ASSERT(m_styleSheet->id() == m_cssId.styleSheetId());
>-        return String::format("SetStyleText %s:%u", m_styleSheet->id().utf8().data(), m_cssId.ordinal());
>+        return makeString("SetStyleText ", m_styleSheet->id(), ':', m_cssId.ordinal());
>     }
> 
>     void merge(std::unique_ptr<Action> action) override
>diff --git a/Source/WebCore/inspector/agents/InspectorIndexedDBAgent.cpp b/Source/WebCore/inspector/agents/InspectorIndexedDBAgent.cpp
>index 96bc87ef8c1afd897bd26bf2269e4105594dea8a..6d5881ea0e664cbbce2a85f8d9de093fb43ccac0 100644
>--- a/Source/WebCore/inspector/agents/InspectorIndexedDBAgent.cpp
>+++ b/Source/WebCore/inspector/agents/InspectorIndexedDBAgent.cpp
>@@ -68,6 +68,7 @@
> #include <wtf/JSONValues.h>
> #include <wtf/NeverDestroyed.h>
> #include <wtf/Vector.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> using JSON::ArrayOf;
> using Inspector::Protocol::IndexedDB::DatabaseWithObjectStores;
>@@ -711,7 +712,7 @@ public:
>             auto result = idbObjectStore->clear(*exec);
>             ASSERT(!result.hasException());
>             if (result.hasException()) {
>-                m_requestCallback->sendFailure(String::format("Could not clear object store '%s': %d", m_objectStoreName.utf8().data(), result.releaseException().code()));
>+                m_requestCallback->sendFailure(makeString("Could not clear object store '", m_objectStoreName, "': ", static_cast<int>(result.releaseException().code())));
>                 return;
>             }
>             idbRequest = result.releaseReturnValue();
>diff --git a/Source/WebCore/page/MemoryRelease.cpp b/Source/WebCore/page/MemoryRelease.cpp
>index 08f04a46dcbcfd422d3983fb0a3b55f3837a093b..1f5f63308433eea0eec18b497567d963d11ce299 100644
>--- a/Source/WebCore/page/MemoryRelease.cpp
>+++ b/Source/WebCore/page/MemoryRelease.cpp
>@@ -169,7 +169,7 @@ void logMemoryStatisticsAtTimeOfDeath()
>             continue;
>         String tagName = displayNameForVMTag(i);
>         if (!tagName)
>-            tagName = String::format("Tag %u", i);
>+            tagName = makeString("Tag ", i);
>         RELEASE_LOG(MemoryPressure, "%16s: %lu MB", tagName.latin1().data(), dirty / MB);
>     }
> #endif
>diff --git a/Source/WebCore/page/cocoa/ResourceUsageOverlayCocoa.mm b/Source/WebCore/page/cocoa/ResourceUsageOverlayCocoa.mm
>index 4b5c631096321184c68a12e2f6abb03f8d7a9df5..fdf4a230eaeab08eb30e76cc42cceecd30a5abf3 100644
>--- a/Source/WebCore/page/cocoa/ResourceUsageOverlayCocoa.mm
>+++ b/Source/WebCore/page/cocoa/ResourceUsageOverlayCocoa.mm
>@@ -431,7 +431,7 @@ static String formatByteNumber(size_t number)
>         return String::format("%.2f MB", static_cast<double>(number) / 1048576);
>     if (number >= 1024)
>         return String::format("%.1f kB", static_cast<double>(number) / 1024);
>-    return String::format("%lu", number);
>+    return String::number(number);
> }
> 
> static String gcTimerString(MonotonicTime timerFireDate, MonotonicTime now)
>@@ -469,9 +469,9 @@ void ResourceUsageOverlay::platformDraw(CGContextRef context)
>         
>         String label = String::format("% 11s: %s", category.name.ascii().data(), formatByteNumber(dirty).ascii().data());
>         if (external)
>-            label = label + String::format(" + %s", formatByteNumber(external).ascii().data());
>+            label = label + makeString(" + ", formatByteNumber(external));
>         if (reclaimable)
>-            label = label + String::format(" [%s]", formatByteNumber(reclaimable).ascii().data());
>+            label = label + makeString(" [", formatByteNumber(reclaimable), ']');
> 
>         // FIXME: Show size/capacity of GC heap.
>         showText(context, 10, y, category.color.get(), label);
>@@ -480,8 +480,8 @@ void ResourceUsageOverlay::platformDraw(CGContextRef context)
>     y -= 5;
> 
>     MonotonicTime now = MonotonicTime::now();
>-    showText(context, 10, y + 10, colorForLabels, String::format("    Eden GC: %s", gcTimerString(data.timeOfNextEdenCollection, now).ascii().data()));
>-    showText(context, 10, y + 20, colorForLabels, String::format("    Full GC: %s", gcTimerString(data.timeOfNextFullCollection, now).ascii().data()));
>+    showText(context, 10, y + 10, colorForLabels, "    Eden GC: " + gcTimerString(data.timeOfNextEdenCollection, now));
>+    showText(context, 10, y + 20, colorForLabels, "    Full GC: " + gcTimerString(data.timeOfNextFullCollection, now));
> 
>     drawCpuHistory(context, viewBounds.size.width - 70, 0, viewBounds.size.height, data.cpu);
>     drawGCHistory(context, viewBounds.size.width - 140, 0, viewBounds.size.height, data.gcHeapSize, data.categories[MemoryCategory::GCHeap].dirtySize);
>diff --git a/Source/WebCore/page/cocoa/ResourceUsageThreadCocoa.mm b/Source/WebCore/page/cocoa/ResourceUsageThreadCocoa.mm
>index d8e54be9d34361bac46a215a38a3c1fa0fede7b9..8956172e71031e4e9c6b72d37c750127250e9d63 100644
>--- a/Source/WebCore/page/cocoa/ResourceUsageThreadCocoa.mm
>+++ b/Source/WebCore/page/cocoa/ResourceUsageThreadCocoa.mm
>@@ -36,6 +36,7 @@
> #include <mach/vm_statistics.h>
> #include <pal/spi/cocoa/MachVMSPI.h>
> #include <wtf/MachSendRight.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -63,7 +64,7 @@ void logFootprintComparison(const std::array<TagInfo, 256>& before, const std::a
>             continue;
>         String tagName = displayNameForVMTag(i);
>         if (!tagName)
>-            tagName = String::format("Tag %u", i);
>+            tagName = makeString("Tag ", i);
>         WTFLogAlways("  %02X %16s %10ld %10ld %10ld",
>             i,
>             tagName.ascii().data(),
>diff --git a/Source/WebCore/platform/animation/TimingFunction.cpp b/Source/WebCore/platform/animation/TimingFunction.cpp
>index cfd0b36027939d4b86afd6fe7e873e04fb86ff65..9407342065fe9fc528d54574446376a1d4d7d7dc 100644
>--- a/Source/WebCore/platform/animation/TimingFunction.cpp
>+++ b/Source/WebCore/platform/animation/TimingFunction.cpp
>@@ -30,6 +30,7 @@
> #include "SpringSolver.h"
> #include "StyleProperties.h"
> #include "UnitBezier.h"
>+#include <wtf/text/StringConcatenateNumbers.h>
> #include <wtf/text/TextStream.h>
> 
> namespace WebCore {
>@@ -181,7 +182,7 @@ String TimingFunction::cssText() const
>     if (m_type == TimingFunction::StepsFunction) {
>         auto& function = downcast<StepsTimingFunction>(*this);
>         if (!function.stepAtStart())
>-            return String::format("steps(%d)", function.numberOfSteps());
>+            return makeString("steps(", function.numberOfSteps(), ')');
>     }
> 
>     TextStream stream;
>diff --git a/Source/WebCore/platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm b/Source/WebCore/platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm
>index 6e48fdaf1859070a26934bcb606fe5a40cfbde2c..eb6988840a1307157831fe38aab23f0e85a8be74 100644
>--- a/Source/WebCore/platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm
>+++ b/Source/WebCore/platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm
>@@ -180,7 +180,7 @@ int AVTrackPrivateAVFObjCImpl::index() const
> AtomicString AVTrackPrivateAVFObjCImpl::id() const
> {
>     if (m_assetTrack)
>-        return String::format("%d", [m_assetTrack trackID]);
>+        return AtomicString::number([m_assetTrack trackID]);
>     if (m_mediaSelectionOption)
>         return [[m_mediaSelectionOption->avMediaSelectionOption() optionID] stringValue];
>     ASSERT_NOT_REACHED();
>diff --git a/Source/WebCore/platform/graphics/avfoundation/objc/MediaSampleAVFObjC.h b/Source/WebCore/platform/graphics/avfoundation/objc/MediaSampleAVFObjC.h
>index 60ee96f402433622f5854126ffb239510698ce31..966ccd5569f9e06b6f9a581997aa7b389d1dd230 100644
>--- a/Source/WebCore/platform/graphics/avfoundation/objc/MediaSampleAVFObjC.h
>+++ b/Source/WebCore/platform/graphics/avfoundation/objc/MediaSampleAVFObjC.h
>@@ -84,7 +84,7 @@ protected:
>     }
>     MediaSampleAVFObjC(CMSampleBufferRef sample, int trackID)
>         : m_sample(sample)
>-        , m_id(String::format("%d", trackID))
>+        , m_id(AtomicString::number(trackID))
>     {
>     }
>     MediaSampleAVFObjC(CMSampleBufferRef sample, VideoRotation rotation, bool mirrored)
>diff --git a/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp b/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
>index e4f67cd1ab39d8d96dbbd60e6b32d0022650f3f1..97788fa09349af2f12049bda0f324795170c7008 100644
>--- a/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
>+++ b/Source/WebCore/platform/graphics/ca/GraphicsLayerCA.cpp
>@@ -52,8 +52,8 @@
> #include <wtf/NeverDestroyed.h>
> #include <wtf/SetForScope.h>
> #include <wtf/SystemTracing.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> #include <wtf/text/TextStream.h>
>-#include <wtf/text/WTFString.h>
> 
> #if PLATFORM(IOS_FAMILY)
> #include "SystemMemory.h"
>@@ -1101,7 +1101,7 @@ void GraphicsLayerCA::setContentsToSolidColor(const Color& color)
>             m_contentsLayerPurpose = ContentsLayerPurpose::BackgroundColor;
>             m_contentsLayer = createPlatformCALayer(PlatformCALayer::LayerTypeLayer, this);
> #if ENABLE(TREE_DEBUGGING)
>-            m_contentsLayer->setName(String::format("contents color %llu", m_contentsLayer->layerID()));
>+            m_contentsLayer->setName(makeString("contents color ", m_contentsLayer->layerID()));
> #else
>             m_contentsLayer->setName("contents color");
> #endif
>@@ -2566,7 +2566,7 @@ void GraphicsLayerCA::updateContentsImage()
>         if (!m_contentsLayer.get()) {
>             m_contentsLayer = createPlatformCALayer(PlatformCALayer::LayerTypeLayer, this);
> #if ENABLE(TREE_DEBUGGING)
>-            m_contentsLayer->setName(String::format("contents image %llu", m_contentsLayer->layerID()));
>+            m_contentsLayer->setName(makeString("contents image ", m_contentsLayer->layerID()));
> #else
>             m_contentsLayer->setName("contents image");
> #endif
>@@ -2672,7 +2672,7 @@ void GraphicsLayerCA::updateContentsRects()
>             m_contentsClippingLayer = createPlatformCALayer(PlatformCALayer::LayerTypeLayer, this);
>             m_contentsClippingLayer->setAnchorPoint(FloatPoint());
> #if ENABLE(TREE_DEBUGGING)
>-            m_contentsClippingLayer->setName(String::format("contents clipping %llu", m_contentsClippingLayer->layerID()));
>+            m_contentsClippingLayer->setName(makeString("contents clipping ", m_contentsClippingLayer->layerID()));
> #else
>             m_contentsClippingLayer->setName("contents clipping");
> #endif
>@@ -3156,7 +3156,7 @@ bool GraphicsLayerCA::appendToUncommittedAnimations(const KeyframeValueList& val
>     for (int internalFilterPropertyIndex = 0; internalFilterPropertyIndex < numAnimatedProperties; ++internalFilterPropertyIndex) {
>         bool valuesOK;
>         RefPtr<PlatformCAAnimation> caAnimation;
>-        String keyPath = String::format("filters.filter_%d.%s", animationIndex, PlatformCAFilters::animatedFilterPropertyName(filterOp, internalFilterPropertyIndex));
>+        String keyPath = makeString("filters.filter_", animationIndex, '.', PlatformCAFilters::animatedFilterPropertyName(filterOp, internalFilterPropertyIndex));
>         
>         if (isKeyframe) {
>             caAnimation = createKeyframeAnimation(animation, keyPath, false);
>@@ -3914,7 +3914,7 @@ RefPtr<PlatformCALayer> GraphicsLayerCA::findOrMakeClone(CloneID cloneID, Platfo
>     } else {
>         resultLayer = cloneLayer(sourceLayer, cloneLevel);
> #if ENABLE(TREE_DEBUGGING)
>-        resultLayer->setName(String::format("clone %d of %llu", cloneID[0U], sourceLayer->layerID()));
>+        resultLayer->setName(makeString("clone ", cloneID[0U], " of ", sourceLayer->layerID()));
> #else
>         resultLayer->setName("clone of " + m_name);
> #endif
>diff --git a/Source/WebCore/platform/mock/MockRealtimeVideoSource.cpp b/Source/WebCore/platform/mock/MockRealtimeVideoSource.cpp
>index 1ff6c30c7c4eae237afd3f72c326141062575fcb..a48e14fdf25df742ccf384bf2b054c921fb5bc64 100644
>--- a/Source/WebCore/platform/mock/MockRealtimeVideoSource.cpp
>+++ b/Source/WebCore/platform/mock/MockRealtimeVideoSource.cpp
>@@ -44,7 +44,7 @@
> #include "RealtimeMediaSourceSettings.h"
> #include <math.h>
> #include <wtf/UUID.h>
>-#include <wtf/text/StringView.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -367,12 +367,12 @@ void MockRealtimeVideoSource::drawText(GraphicsContext& context)
> 
>     auto size = this->size();
>     statsLocation.move(0, m_statsFontSize);
>-    string = String::format("Size: %u x %u", size.width(), size.height());
>+    string = makeString("Size: ", size.width(), " x ", size.height());
>     context.drawText(statsFont, TextRun((StringView(string))), statsLocation);
> 
>     if (mockCamera()) {
>         statsLocation.move(0, m_statsFontSize);
>-        string = String::format("Preset size: %u x %u", captureSize.width(), captureSize.height());
>+        string = makeString("Preset size: ", captureSize.width(), " x ", captureSize.height());
>         context.drawText(statsFont, TextRun((StringView(string))), statsLocation);
> 
>         const char* camera;
>@@ -393,7 +393,7 @@ void MockRealtimeVideoSource::drawText(GraphicsContext& context)
>             camera = "Unknown";
>             break;
>         }
>-        string = String::format("Camera: %s", camera);
>+        string = makeString("Camera: ", camera);
>         statsLocation.move(0, m_statsFontSize);
>         context.drawText(statsFont, TextRun((StringView(string))), statsLocation);
>     } else if (!name().isNull()) {
>diff --git a/Source/WebCore/platform/mock/mediasource/MockSourceBufferPrivate.cpp b/Source/WebCore/platform/mock/mediasource/MockSourceBufferPrivate.cpp
>index 9fbac0020478e9b350de7ff4d47c9fe359460e1e..ce273f17f1670bbee3e469b8f238540c97b9974a 100644
>--- a/Source/WebCore/platform/mock/mediasource/MockSourceBufferPrivate.cpp
>+++ b/Source/WebCore/platform/mock/mediasource/MockSourceBufferPrivate.cpp
>@@ -49,7 +49,7 @@ public:
> private:
>     MockMediaSample(const MockSampleBox& box)
>         : m_box(box)
>-        , m_id(String::format("%d", box.trackID()))
>+        , m_id(String::number(box.trackID()))
>     {
>     }
> 
>diff --git a/Source/WebCore/platform/network/ParsedContentRange.cpp b/Source/WebCore/platform/network/ParsedContentRange.cpp
>index 00b90c4853e8e20bb4e92857af0e17e9150df425..a3d4f044059dfd9a57b31929db8f112c15f62113 100644
>--- a/Source/WebCore/platform/network/ParsedContentRange.cpp
>+++ b/Source/WebCore/platform/network/ParsedContentRange.cpp
>@@ -27,7 +27,7 @@
> #include "ParsedContentRange.h"
> 
> #include <wtf/StdLibExtras.h>
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -127,8 +127,8 @@ String ParsedContentRange::headerValue() const
>     if (!m_isValid)
>         return String();
>     if (m_instanceLength == UnknownLength)
>-        return String::format("bytes %" PRId64 "-%" PRId64 "/*", m_firstBytePosition, m_lastBytePosition);
>-    return String::format("bytes %" PRId64 "-%" PRId64 "/%" PRId64, m_firstBytePosition, m_lastBytePosition, m_instanceLength);
>+        return makeString("bytes ", m_firstBytePosition, '-', m_lastBytePosition, "/*");
>+    return makeString("bytes ", m_firstBytePosition, '-', m_lastBytePosition, '/', m_instanceLength);
> }
> 
> }
>diff --git a/Source/WebCore/platform/network/cf/NetworkStorageSessionCFNet.cpp b/Source/WebCore/platform/network/cf/NetworkStorageSessionCFNet.cpp
>index 09d86d0fecf09a66dd398494c79bbaf079e4bc60..b01a7e66bf0914961d63010741e22175f9efb9b8 100644
>--- a/Source/WebCore/platform/network/cf/NetworkStorageSessionCFNet.cpp
>+++ b/Source/WebCore/platform/network/cf/NetworkStorageSessionCFNet.cpp
>@@ -30,6 +30,7 @@
> #include <wtf/NeverDestroyed.h>
> #include <wtf/ProcessID.h>
> #include <wtf/ProcessPrivilege.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> #if PLATFORM(COCOA)
> #include "PublicSuffix.h"
>diff --git a/Source/WebCore/platform/sql/SQLiteDatabase.cpp b/Source/WebCore/platform/sql/SQLiteDatabase.cpp
>index 663e0bc0b8567083aa97ef8115a5468c517e96c5..d7bc6132b42686de49e58da284d667d97ab73694 100644
>--- a/Source/WebCore/platform/sql/SQLiteDatabase.cpp
>+++ b/Source/WebCore/platform/sql/SQLiteDatabase.cpp
>@@ -46,8 +46,7 @@ static const char notOpenErrorMessage[] = "database is not open";
> static void unauthorizedSQLFunction(sqlite3_context *context, int, sqlite3_value **)
> {
>     const char* functionName = (const char*)sqlite3_user_data(context);
>-    String errorMessage = String::format("Function %s is unauthorized", functionName);
>-    sqlite3_result_error(context, errorMessage.utf8().data(), -1);
>+    sqlite3_result_error(context, makeString("Function ", functionName, " is unauthorized").utf8().data(), -1);
> }
> 
> static void initializeSQLiteIfNecessary()
>diff --git a/Source/WebCore/rendering/RenderLayerCompositor.cpp b/Source/WebCore/rendering/RenderLayerCompositor.cpp
>index 5b1ca4c95d6d1006e47428731493b4b083869d00..88bc5d15354c6b3d8f0bc4a23ce34db1916ee0a9 100644
>--- a/Source/WebCore/rendering/RenderLayerCompositor.cpp
>+++ b/Source/WebCore/rendering/RenderLayerCompositor.cpp
>@@ -1278,7 +1278,7 @@ void RenderLayerCompositor::logLayerInfo(const RenderLayer& layer, const char* p
>         backing->backingStoreMemoryEstimate() / 1024));
>     
>     if (!layer.renderer().style().hasAutoZIndex())
>-        logString.append(String::format(" z-index: %d", layer.renderer().style().zIndex())); 
>+        logString.append(makeString(" z-index: ", layer.renderer().style().zIndex()));
> 
>     logString.appendLiteral(" (");
>     logString.append(logReasonsForCompositing(layer));
>diff --git a/Source/WebCore/workers/service/server/RegistrationDatabase.cpp b/Source/WebCore/workers/service/server/RegistrationDatabase.cpp
>index 1af43788fffbaaa912e1ad97bbd98b172de3f0e3..56dd9bc8e3305388bbf577f56ae65261d24ae379 100644
>--- a/Source/WebCore/workers/service/server/RegistrationDatabase.cpp
>+++ b/Source/WebCore/workers/service/server/RegistrationDatabase.cpp
>@@ -45,6 +45,7 @@
> #include <wtf/persistence/PersistentCoders.h>
> #include <wtf/persistence/PersistentDecoder.h>
> #include <wtf/persistence/PersistentEncoder.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebCore {
> 
>@@ -201,7 +202,7 @@ String RegistrationDatabase::ensureValidRecordsTable()
>         // If there is no Records table at all, create it and then bail.
>         if (sqliteResult == SQLITE_DONE) {
>             if (!m_database->executeCommand(recordsTableSchema()))
>-                return String::format("Could not create Records table in database (%i) - %s", m_database->lastError(), m_database->lastErrorMsg());
>+                return makeString("Could not create Records table in database (", m_database->lastError(), ") - ", m_database->lastErrorMsg());
>             return { };
>         }
> 
>@@ -359,7 +360,7 @@ String RegistrationDatabase::importRecords()
> 
>     SQLiteStatement sql(*m_database, "SELECT * FROM Records;"_s);
>     if (sql.prepare() != SQLITE_OK)
>-        return String::format("Failed to prepare statement to retrieve registrations from records table (%i) - %s", m_database->lastError(), m_database->lastErrorMsg());
>+        return makeString("Failed to prepare statement to retrieve registrations from records table (", m_database->lastError(), ") - ", m_database->lastErrorMsg());
> 
>     int result = sql.step();
> 
>@@ -411,7 +412,7 @@ String RegistrationDatabase::importRecords()
>     }
> 
>     if (result != SQLITE_DONE)
>-        return String::format("Failed to import at least one registration from records table (%i) - %s", m_database->lastError(), m_database->lastErrorMsg());
>+        return makeString("Failed to import at least one registration from records table (", m_database->lastError(), ") - ", m_database->lastErrorMsg());
> 
>     return { };
> }
>diff --git a/Source/WebKit/Shared/WebMemorySampler.cpp b/Source/WebKit/Shared/WebMemorySampler.cpp
>index 2b85200dec9278c74dbaf62ae5330d9f8d37dc07..87e6eeb3a9431e5c5727fa525b71fd756ebceaa1 100644
>--- a/Source/WebKit/Shared/WebMemorySampler.cpp
>+++ b/Source/WebKit/Shared/WebMemorySampler.cpp
>@@ -32,6 +32,7 @@
> #include <wtf/ProcessID.h>
> #include <wtf/text/CString.h>
> #include <wtf/text/StringBuilder.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebKit {
> using namespace WebCore;
>@@ -142,7 +143,7 @@ void WebMemorySampler::initializeSandboxedLogFile(SandboxExtension::Handle&& sam
> 
> void WebMemorySampler::writeHeaders()
> {
>-    String processDetails = String::format("Process: %s Pid: %d\n", processName().utf8().data(), getCurrentProcessID());
>+    String processDetails = makeString("Process: ", processName(), " Pid: ", getCurrentProcessID(), '\n');
> 
>     CString utf8String = processDetails.utf8();
>     FileSystem::writeToFile(m_sampleLogFile, utf8String.data(), utf8String.length());
>diff --git a/Source/WebKit/UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm b/Source/WebKit/UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm
>index efc3e160b48bc6e3b7dae544a522347c978b9328..9c27727e87261741a203d70bc1ab21d7b51d517d 100644
>--- a/Source/WebKit/UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm
>+++ b/Source/WebKit/UIProcess/WebAuthentication/Cocoa/LocalAuthenticator.mm
>@@ -152,7 +152,7 @@ void LocalAuthenticator::makeCredential()
>         weakThis->continueMakeCredentialAfterUserConsented(consent);
>     };
>     m_connection->getUserConsent(
>-        String::format("Allow %s to create a public key credential for %s", requestData().creationOptions.rp.id.utf8().data(), requestData().creationOptions.user.name.utf8().data()),
>+        "Allow " + requestData().creationOptions.rp.id + " to create a public key credential for " + requestData().creationOptions.user.name,
>         WTFMove(callback));
> #endif // !PLATFORM(IOS_FAMILY)
> }
>diff --git a/Source/WebKit/UIProcess/WebInspectorUtilities.cpp b/Source/WebKit/UIProcess/WebInspectorUtilities.cpp
>index c5db401ee1c61958942d6a3b30cf30f13fa6b806..3b49ce034a9aab0323db14b33608deba64ffbf98 100644
>--- a/Source/WebKit/UIProcess/WebInspectorUtilities.cpp
>+++ b/Source/WebKit/UIProcess/WebInspectorUtilities.cpp
>@@ -33,6 +33,7 @@
> #include "WebProcessProxy.h"
> #include <wtf/HashMap.h>
> #include <wtf/NeverDestroyed.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WebKit {
> 
>@@ -57,7 +58,7 @@ unsigned inspectorLevelForPage(WebPageProxy* page)
> 
> String inspectorPageGroupIdentifierForPage(WebPageProxy* page)
> {
>-    return String::format("__WebInspectorPageGroupLevel%u__", inspectorLevelForPage(page));
>+    return makeString("__WebInspectorPageGroupLevel", inspectorLevelForPage(page), "__");
> }
> 
> void trackInspectorPage(WebPageProxy* page)
>diff --git a/Source/WebKit/UIProcess/WebProcessPool.cpp b/Source/WebKit/UIProcess/WebProcessPool.cpp
>index d2f6a67f62da1d8e50841ea9ea7651ba13c2ac67..9e64800160f6c21411c7325a7d9e558047b88b3b 100644
>--- a/Source/WebKit/UIProcess/WebProcessPool.cpp
>+++ b/Source/WebKit/UIProcess/WebProcessPool.cpp
>@@ -41,9 +41,6 @@
> #include "DownloadProxyMessages.h"
> #include "GamepadData.h"
> #include "HighPerformanceGraphicsUsageSampler.h"
>-#if ENABLE(LEGACY_CUSTOM_PROTOCOL_MANAGER)
>-#include "LegacyCustomProtocolManagerMessages.h"
>-#endif
> #include "LogInitialization.h"
> #include "Logging.h"
> #include "NetworkProcessCreationParameters.h"
>@@ -98,6 +95,11 @@
> #include <wtf/URLParser.h>
> #include <wtf/WallTime.h>
> #include <wtf/text/StringBuilder.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
>+
>+#if ENABLE(LEGACY_CUSTOM_PROTOCOL_MANAGER)
>+#include "LegacyCustomProtocolManagerMessages.h"
>+#endif
> 
> #if ENABLE(SERVICE_CONTROLS)
> #include "ServicesController.h"
>@@ -1019,7 +1021,7 @@ void WebProcessPool::processDidFinishLaunching(WebProcessProxy* process)
>     if (m_memorySamplerEnabled) {
>         SandboxExtension::Handle sampleLogSandboxHandle;        
>         WallTime now = WallTime::now();
>-        String sampleLogFilePath = String::format("WebProcess%llupid%d", static_cast<unsigned long long>(now.secondsSinceEpoch().seconds()), process->processIdentifier());
>+        String sampleLogFilePath = makeString("WebProcess", static_cast<unsigned long long>(now.secondsSinceEpoch().seconds()), "pid", process->processIdentifier());
>         sampleLogFilePath = SandboxExtension::createHandleForTemporaryFile(sampleLogFilePath, SandboxExtension::Type::ReadWrite, sampleLogSandboxHandle);
>         
>         process->send(Messages::WebProcess::StartMemorySampler(sampleLogSandboxHandle, sampleLogFilePath, m_memorySamplerInterval), 0);
>@@ -1577,7 +1579,7 @@ void WebProcessPool::startMemorySampler(const double interval)
>     // For WebProcess
>     SandboxExtension::Handle sampleLogSandboxHandle;    
>     WallTime now = WallTime::now();
>-    String sampleLogFilePath = String::format("WebProcess%llu", static_cast<unsigned long long>(now.secondsSinceEpoch().seconds()));
>+    String sampleLogFilePath = makeString("WebProcess", static_cast<unsigned long long>(now.secondsSinceEpoch().seconds()));
>     sampleLogFilePath = SandboxExtension::createHandleForTemporaryFile(sampleLogFilePath, SandboxExtension::Type::ReadWrite, sampleLogSandboxHandle);
>     
>     sendToAllProcesses(Messages::WebProcess::StartMemorySampler(sampleLogSandboxHandle, sampleLogFilePath, interval));
>diff --git a/Source/WebKitLegacy/WebCoreSupport/NetworkStorageSessionMap.cpp b/Source/WebKitLegacy/WebCoreSupport/NetworkStorageSessionMap.cpp
>index 470796a6dcac33dea6391443dbcf712dd03a9c38..584f0a163c8c3a513bf735439f7134112ba3f98f 100644
>--- a/Source/WebKitLegacy/WebCoreSupport/NetworkStorageSessionMap.cpp
>+++ b/Source/WebKitLegacy/WebCoreSupport/NetworkStorageSessionMap.cpp
>@@ -30,6 +30,7 @@
> #include <wtf/MainThread.h>
> #include <wtf/ProcessID.h>
> #include <wtf/ProcessPrivilege.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> static std::unique_ptr<WebCore::NetworkStorageSession>& defaultNetworkStorageSession()
> {
>@@ -67,7 +68,7 @@ void NetworkStorageSessionMap::switchToNewTestingSession()
> {
> #if PLATFORM(COCOA) || USE(CFURLCONNECTION)
>     // Session name should be short enough for shared memory region name to be under the limit, otehrwise sandbox rules won't work (see <rdar://problem/13642852>).
>-    String sessionName = String::format("WebKit Test-%u", static_cast<uint32_t>(getCurrentProcessID()));
>+    String sessionName = makeString("WebKit Test-", getCurrentProcessID());
> 
>     auto session = adoptCF(WebCore::createPrivateStorageSession(sessionName.createCFString().get()));
> 
>diff --git a/Tools/ChangeLog b/Tools/ChangeLog
>index 01cb3b9862caf9c13465c518e218361db5aded56..7f994b58c3f8462ae6237f1f0b977cdab2a01608 100644
>--- a/Tools/ChangeLog
>+++ b/Tools/ChangeLog
>@@ -1,3 +1,16 @@
>+2018-12-15  Darin Adler  <darin@apple.com>
>+
>+        Replace many uses of String::format with more type-safe alternatives
>+        https://bugs.webkit.org/show_bug.cgi?id=192742
>+
>+        Reviewed by Mark Lam.
>+
>+        * WebKitTestRunner/InjectedBundle/TestRunner.cpp:
>+        (WTR::cacheTestRunnerCallback): Use makeString.
>+        * WebKitTestRunner/TestController.cpp:
>+        (WTR::TestController::didReceiveAuthenticationChallenge): Use makeString.
>+        (WTR::TestController::downloadDidFail): Use an ASCIILiteral via the _s syntax.
>+
> 2019-01-27  Jiewen Tan  <jiewen_tan@apple.com>
> 
>         Use a load optimizer for some sites
>diff --git a/Tools/WebKitTestRunner/InjectedBundle/TestRunner.cpp b/Tools/WebKitTestRunner/InjectedBundle/TestRunner.cpp
>index 40d4129b1ecd0fd54bc883beabe192a1a373b580..100ab7c40f738929d926ce8469f106732d207d68 100644
>--- a/Tools/WebKitTestRunner/InjectedBundle/TestRunner.cpp
>+++ b/Tools/WebKitTestRunner/InjectedBundle/TestRunner.cpp
>@@ -55,6 +55,7 @@
> #include <wtf/StdLibExtras.h>
> #include <wtf/text/CString.h>
> #include <wtf/text/StringBuilder.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> namespace WTR {
> 
>@@ -813,7 +814,7 @@ static void cacheTestRunnerCallback(unsigned index, JSValueRef callback)
>         return;
> 
>     if (callbackMap().contains(index)) {
>-        InjectedBundle::singleton().outputText(String::format("FAIL: Tried to install a second TestRunner callback for the same event (id %d)\n\n", index));
>+        InjectedBundle::singleton().outputText(makeString("FAIL: Tried to install a second TestRunner callback for the same event (id ", index, ")\n\n"));
>         return;
>     }
> 
>diff --git a/Tools/WebKitTestRunner/TestController.cpp b/Tools/WebKitTestRunner/TestController.cpp
>index 7b662aa6000c6048b37f4eaa8f4019d120096252..0cff71956db9c428bb517b4d6cd3accb941be4d8 100644
>--- a/Tools/WebKitTestRunner/TestController.cpp
>+++ b/Tools/WebKitTestRunner/TestController.cpp
>@@ -78,7 +78,7 @@
> #include <wtf/SetForScope.h>
> #include <wtf/UUID.h>
> #include <wtf/text/CString.h>
>-#include <wtf/text/WTFString.h>
>+#include <wtf/text/StringConcatenateNumbers.h>
> 
> #if PLATFORM(COCOA)
> #include <WebKit/WKContextPrivateMac.h>
>@@ -2073,11 +2073,11 @@ void TestController::didReceiveAuthenticationChallenge(WKPageRef page, WKAuthent
> 
>     std::string host = toSTD(adoptWK(WKProtectionSpaceCopyHost(protectionSpace)).get());
>     int port = WKProtectionSpaceGetPort(protectionSpace);
>-    String message = String::format("%s:%d - didReceiveAuthenticationChallenge - %s - ", host.c_str(), port, toString(authenticationScheme));
>+    String message = makeString(host.c_str(), ':', port, " - didReceiveAuthenticationChallenge - ", toString(authenticationScheme), " - ");
>     if (!m_handlesAuthenticationChallenges)
>         message.append("Simulating cancelled authentication sheet\n");
>     else
>-        message.append(String::format("Responding with %s:%s\n", m_authenticationUsername.utf8().data(), m_authenticationPassword.utf8().data()));
>+        message.append("Responding with " + m_authenticationUsername + ":" + m_authenticationPassword + "\n");
>     m_currentInvocation->outputText(message);
> 
>     if (!m_handlesAuthenticationChallenges) {
>@@ -2175,8 +2175,7 @@ void TestController::downloadDidReceiveServerRedirectToURL(WKContextRef, WKDownl
> void TestController::downloadDidFail(WKContextRef, WKDownloadRef, WKErrorRef error)
> {
>     if (m_shouldLogDownloadCallbacks) {
>-        String message = String::format("Download failed.\n");
>-        m_currentInvocation->outputText(message);
>+        m_currentInvocation->outputText("Download failed.\n"_s);
> 
>         WKRetainPtr<WKStringRef> errorDomain = adoptWK(WKErrorCopyDomain(error));
>         WKRetainPtr<WKStringRef> errorDescription = adoptWK(WKErrorCopyLocalizedDescription(error));

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Attachments on bug 192742: 357404 | 357406 | 360243 | 360311