Reviewed by Sam Weinig.

        Remove the isActivationObject() virtual method on JSObject and use
        StructureID information instead. This should be slightly faster, but
        isActivationObject() is only used in assertions and unwinding the stack
        for exceptions.

        * VM/Machine.cpp:
        (JSC::depth):
        (JSC::Machine::unwindCallFrame):
        (JSC::Machine::privateExecute):
        (JSC::Machine::cti_op_ret_activation):
        * kjs/JSActivation.cpp:
        * kjs/JSActivation.h:
        * kjs/JSObject.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@37068 268f45cc-cd09-0410-ab3c-d52691b4dbfc