Reviewed by Geoffrey Garen.

        Rubber-stamped by Maciej Stachowiak.

        A few of Maciej's review suggestions for my last patch.
        https://bugs.webkit.org/show_bug.cgi?id=52946        

        SunSpider reports no change.

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

        * runtime/ConservativeSet.cpp: Added.
        (JSC::isPointerAligned):
        (JSC::ConservativeSet::add):
        * runtime/ConservativeSet.h: Added.
        (JSC::ConservativeSet::ConservativeSet):
        (JSC::ConservativeSet::mark): Split ConservativeSet out into its own
        file, and moved the conservative check into ConservativeSet::add, making
        ConservativeSet's responsibility clearer.

        * runtime/Heap.cpp:
        (JSC::Heap::markRoots):
        * runtime/MachineStackMarker.cpp:
        (JSC::MachineStackMarker::markCurrentThreadConservativelyInternal):
        (JSC::MachineStackMarker::markOtherThreadConservatively):
        * runtime/MachineStackMarker.h:
        * runtime/MarkStack.h: Updated for changes above.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@76454 268f45cc-cd09-0410-ab3c-d52691b4dbfc