<rdar://problem/23725315>

Will implement the DFG and FTL bits in one go in https://bugs.webkit.org/show_bug.cgi?id=151746 instead. This is because there are perf tests (in JSRegress) that will show a regression if we implement only the DFG part first. The perceived regression is not actually due to the polymorphic mul under-performing, but rather due to the FTL not being able to compile the test function if we don't already support polymorphic mul in the FTL. The mul operator is in a code path that doesn't actually gets exercised by the tests, but the FTL makes the rest of the function runs much faster. Without the FTL, the test function runs slower due to no fault of the mul operator, other than its presence making the function not compilable by the FTL. By implementing DFG and FTL support in one go, we avoid this issue altogether. *** This bug has been marked as a duplicate of bug 151746 ***