Reviewed by John.

    Reviewed by John.

        <rdar://problem/5204792> REGRESSION (r21367): System widgets are drawn with vertical/horizontal scroll bars

        No test because the bug requires calling setAllowsScrolling: to reproduce.

        * WebView/WebFrameView.mm:
        (-[WebFrameView setAllowsScrolling:]): Update the FrameView's scroll state as well as the one
        on WebDynamicScrollBarsView, otherwise this setting won't stick if the frame has already loaded
        a document.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@21575 268f45cc-cd09-0410-ab3c-d52691b4dbfc