Reviewed by Geoff.

    Reviewed by Geoff.

        - better fix for http://bugzilla.opendarwin.org/show_bug.cgi?id=9622
          REGRESSION: showModalDialog returnValue ignored, function result is always "undefined"

        * bindings/js/kjs_window.cpp:
        (KJS::showModalDialog): Set the return value after returning from the function if the
        window is not cleared; this is a better way to handle the case where the window does
        not get cleared before returning, and handles some new cases created by slight changes
        in the latest Safari properly too.
        (KJS::Window::clear): Changed logic slightly so we always store the result of getDirect
        into the return value slot -- the old code left the storage untouched if it was 0.
        Also made it only overwrite the return value slot if it's 0.

        * bindings/js/kjs_proxy.h:
        * bindings/js/kjs_proxy.cpp:
        * bindings/js/kjs_window.h:
        * bindings/js/kjs_window.cpp:
        * page/Frame.cpp:
        Roll the previous fix out.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@15239 268f45cc-cd09-0410-ab3c-d52691b4dbfc