Reviewed by Geoff Garen.

        Inline code generation of eq_null/neq_null for CTI.  Uses vptr checking for
        StringObjectsThatAreMasqueradingAsBeingUndefined.  In the long run, the
        masquerading may be handled differently (through the StructureIDs - see bug
        #20823).

        >1% on v8-tests.

        * VM/CTI.cpp:
        (JSC::CTI::emitJumpSlowCaseIfIsJSCell):
        (JSC::CTI::privateCompileMainPass):
        (JSC::CTI::privateCompileSlowCases):
        * VM/CTI.h:
        * VM/Machine.cpp:
        (JSC::Machine::Machine):
        (JSC::Machine::cti_op_eq_null):
        (JSC::Machine::cti_op_neq_null):
        * VM/Machine.h:
        (JSC::Machine::doesMasqueradesAsUndefined):
        * kjs/JSWrapperObject.h:
        (JSC::JSWrapperObject::):
        (JSC::JSWrapperObject::JSWrapperObject):
        * kjs/StringObject.h:
        (JSC::StringObject::StringObject):
        * kjs/StringObjectThatMasqueradesAsUndefined.h:
        (JSC::StringObjectThatMasqueradesAsUndefined::StringObjectThatMasqueradesAsUndefined):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@36462 268f45cc-cd09-0410-ab3c-d52691b4dbfc