Bug 197530

The following layout test is flaky on iOS Simulator Debug imported/w3c/web-platform-tests/workers/WorkerNavigator_appName.htm Probable cause: Test has been a flaky crash on its available history on the dashboard. Running the test by itself with 10000 iterations could not cause a crash. When I use the test runners from the crashing runs I was able to narrow it down to two tests to reproduce this assertion: run-webkit-tests imported/w3c/web-platform-tests/html/browsers/browsing-the-web/read-media/pageload-video.html imported/w3c/web-platform-tests/workers/WorkerNavigator_appName.htm --child-process 1 --ios-simulator --debug When run in that order it will crash. Will crash with the oldest revision I can checkout which is r230021 Will attach full crash log to radar Test was imported in https://trac.webkit.org/changeset/225593/webkit Flakiness Dashboard: https://webkit-test-results.webkit.org/dashboards/flakiness_dashboard.html#showAllRuns=true&tests=imported%2Fw3c%2Fweb-platform-tests%2Fworkers%2FWorkerNavigator_appName.htm Link to Assertion on bots: https://build.webkit.org/results/Apple%20iOS%2012%20Simulator%20Debug%20WK2%20(Tests)/r244820%20(3520)/imported/w3c/web-platform-tests/workers/WorkerNavigator_appName-crash-log.txt Local Crash Log clip: Thread 32 Crashed:: WebCore: Worker 0 JavaScriptCore 0x0000000114ed38d4 WTFCrash + 36 1 com.apple.WebCore 0x00000007a833de49 WTF::AtomicStringImpl::add(WTF::AtomicStringTable&, WTF::StringImpl&) + 137 2 com.apple.WebCore 0x00000007a833dd75 WTF::RefPtr<WTF::AtomicStringImpl, WTF::DumbPtrTraits<WTF::AtomicStringImpl> > WTF::AtomicStringImpl::addWithStringTableProvider<JSC::VM>(JSC::VM&, WTF::StringImpl*) + 85 3 com.apple.WebCore 0x00000007a833dcbf JSC::Identifier::add(JSC::VM*, WTF::StringImpl*) + 63 4 com.apple.WebCore 0x00000007a833dbb9 JSC::Identifier::Identifier(JSC::VM*, WTF::StringImpl*) + 73 5 com.apple.WebCore 0x00000007a833db65 JSC::Identifier::Identifier(JSC::VM*, WTF::StringImpl*) + 37 6 com.apple.WebCore 0x00000007a833d3c4 JSC::Identifier::fromString(JSC::ExecState*, WTF::String const&) + 68