Reviewed by Geoff.

    Reviewed by Geoff.

        <rdar://problem/4775213> REGRESSION: Can't from tab from last link on the page to URL address field
        <rdar://problem/4783926> REGRESSION: Typing tab key enters no text

        The problem is that EventTargetNode::defaultEventHandler() calls event->setDefaultHandled() regardless
        of whether frame->view()->advanceFocus() actually changed the focus.

        Trivial fix is to preventDefault() only if advanceFocus() returns true.

        * No test is possible because DumpRenderTree sets the WebView preference to
        tab to links, and that preference cannot be changed dynamically after
        the webview is initialized. Also, the "tab from last link" is not testable
        because DumpRenderTree uses the WebView for the whole window, so tabs can't
        shift focus out of the WebView regardless.

        * dom/EventTargetNode.cpp:
        (WebCore::EventTargetNode::defaultEventHandler):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@17059 268f45cc-cd09-0410-ab3c-d52691b4dbfc