Implement an abstraction for thread-specific storage, use it to get rid of some static objects.

        SunSpider results were not conclusive, possibly up to 0.2% slowdown.

        * JavaScriptCore.xcodeproj/project.pbxproj:
        * JavaScriptCore.vcproj/WTF/WTF.vcproj:
        Added ThreadSpecific.h

        * wtf/ThreadSpecific.h: Added.
        (WTF::::ThreadSpecific):
        (WTF::::~ThreadSpecific):
        (WTF::::get):
        (WTF::::set):
        (WTF::::destroy):
        (WTF::T):
        (WTF::::operator):
        Only implemented for platforms that use pthreads.

        * kjs/CommonIdentifiers.cpp:
        (KJS::CommonIdentifiers::shared):
        * kjs/CommonIdentifiers.h:
        * kjs/InitializeThreading.cpp:
        (KJS::initializeThreading):
        * kjs/Parser.cpp:
        (KJS::parser):
        * kjs/Parser.h:
        * kjs/identifier.cpp:
        (KJS::identifierTable):
        (KJS::literalIdentifierTable):
        (KJS::Identifier::initializeIdentifierThreading):
        * kjs/identifier.h:
        * kjs/lexer.cpp:
        (KJS::lexer):
        * kjs/lexer.h:
        Make static instances per-thread.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@31936 268f45cc-cd09-0410-ab3c-d52691b4dbfc