Don't throw out compiled code repeatedly
        https://bugs.webkit.org/show_bug.cgi?id=63960

        Reviewed by Gavin Barraclough.

        Stop throwing away all compiled code every time
        we're told to do a full GC.  Instead unlink all
        callsites during such GC passes to maximise the
        number of collectable functions, but otherwise
        leave compiled functions alone.

        * API/JSBase.cpp:
        (JSGarbageCollect):
        * bytecode/CodeBlock.cpp:
        (JSC::CodeBlock::visitAggregate):
        * heap/Heap.cpp:
        (JSC::Heap::collectAllGarbage):
        * heap/MarkStack.h:
        (JSC::MarkStack::shouldUnlinkCalls):
        (JSC::MarkStack::setShouldUnlinkCalls):
        * runtime/JSGlobalData.cpp:
        (JSC::JSGlobalData::recompileAllJSFunctions):
        (JSC::JSGlobalData::releaseExecutableMemory):
        * runtime/RegExp.cpp:
        (JSC::RegExp::compile):
        (JSC::RegExp::invalidateCode):
        * runtime/RegExp.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@90415 268f45cc-cd09-0410-ab3c-d52691b4dbfc