Reviewed by Gavin Barraclough.

        Split machine stack marking functions into their own class (MachineStackMarker)
        https://bugs.webkit.org/show_bug.cgi?id=52088

        * API/APIShims.h:
        (JSC::APIEntryShimWithoutLock::APIEntryShimWithoutLock): Moved registerThread()
        call behind an #ifdef because we shouldn't be registering threads at all
        if we don't support usage on multiple threads.

        * Android.mk:
        * CMakeLists.txt:
        * GNUmakefile.am:
        * JavaScriptCore.gypi:
        * JavaScriptCore.pro:
        * JavaScriptCore.vcproj/JavaScriptCore/JavaScriptCore.vcproj:
        * JavaScriptCore.xcodeproj/project.pbxproj: Updated projects.

        * runtime/Collector.cpp:
        (JSC::Heap::Heap):
        (JSC::Heap::destroy):
        (JSC::Heap::markRoots):
        * runtime/Collector.h:
        (JSC::Heap::machineStackMarker): Moved code to machineStackMarker.

        * runtime/JSGlobalData.h:
        (JSC::JSGlobalData::makeUsableFromMultipleThreads): Removed an unnecessary
        level of indirection, to make Heap less of a God class.

        * runtime/MachineStackMarker.h: Copied from Source/JavaScriptCore/runtime/Collector.h.
        * runtime/MachineStackMarker.cpp: Copied from Source/JavaScriptCore/runtime/Collector.cpp.
        (JSC::MachineStackMarker::MachineStackMarker):
        (JSC::MachineStackMarker::~MachineStackMarker):
        (JSC::MachineStackMarker::makeUsableFromMultipleThreads):
        (JSC::MachineStackMarker::registerThread):
        (JSC::MachineStackMarker::unregisterThread):
        (JSC::MachineStackMarker::markCurrentThreadConservativelyInternal):
        (JSC::MachineStackMarker::markCurrentThreadConservatively):
        (JSC::MachineStackMarker::markOtherThreadConservatively):
        (JSC::MachineStackMarker::markMachineStackConservatively): Moved code from Heap.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@75342 268f45cc-cd09-0410-ab3c-d52691b4dbfc