Reviewed by Maciej Stachowiak.
        
        An additional fix for Bug 26532: Native functions do not correctly unlink
        from optimised callsites when they're collected
        <https://bugs.webkit.org/show_bug.cgi?id=26532> | <rdar://problem/6625385>

        Use "NativeFunctionWrapper" instead of "PrototypeFunction" in cross-frame
        accessors, so the type of object you get to wrap a function is the same,
        regardless of whether the access to the function is cross-frame.
        
        This is faster and more idiomatic than what we had before. It also would
        have avoided Bug 26532 because it would have prevented a conflicting
        PrototypeFunction from being allocated to wrap postMessage, where a
        NativeFunctionWrapper had been allocated previously.
        
        * bindings/js/JSDOMBinding.cpp:
        (WebCore::objectToStringFunctionGetter):
        * bindings/js/JSDOMWindowCustom.cpp:
        (WebCore::nonCachingStaticFunctionGetter):
        * bindings/js/JSHistoryCustom.cpp:
        (WebCore::nonCachingStaticBackFunctionGetter):
        (WebCore::nonCachingStaticForwardFunctionGetter):
        (WebCore::nonCachingStaticGoFunctionGetter):
        * bindings/js/JSLocationCustom.cpp:
        (WebCore::nonCachingStaticReplaceFunctionGetter):
        (WebCore::nonCachingStaticReloadFunctionGetter):
        (WebCore::nonCachingStaticAssignFunctionGetter):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@44877 268f45cc-cd09-0410-ab3c-d52691b4dbfc