Reviewed by Oliver Hunt.
        
        - fixed "REGRESSION (r37297): fast/js/deep-recursion-test takes too long and times out"
        https://bugs.webkit.org/show_bug.cgi?id=21375
        
        The problem is that dynamicGlobalObject had become O(N) in number
        of call frames, but unwinding the stack for an exception called it
        for every call frame, resulting in O(N^2) behavior for an
        exception thrown from inside deep recursion.

        Instead of doing it that way, stash the dynamic global object in JSGlobalData.
        
        * JavaScriptCore.exp:
        * VM/Machine.cpp:
        (JSC::DynamicGlobalObjectScope::DynamicGlobalObjectScope): Helper class to temporarily
        store and later restore a dynamicGlobalObject in JSGlobalData.
        (JSC::DynamicGlobalObjectScope::~DynamicGlobalObjectScope):
        (JSC::Machine::execute): In each version, establish a DynamicGlobalObjectScope.
        For ProgramNode, always establish set new dynamicGlobalObject, for FunctionBody and Eval,
        only if none is currently set.
        * VM/Machine.h:
        * kjs/ExecState.h:
        * kjs/JSGlobalData.cpp:
        (JSC::JSGlobalData::JSGlobalData): Ininitalize new dynamicGlobalObject field to 0.
        * kjs/JSGlobalData.h:
        * kjs/JSGlobalObject.h:
        (JSC::ExecState::dynamicGlobalObject): Moved here from ExecState for benefit of inlining.
        Return lexical global object if this is a globalExec(), otherwise look in JSGlobalData
        for the one stashed there.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@37323 268f45cc-cd09-0410-ab3c-d52691b4dbfc