Zooming in SVGs in <object> is flakey
        https://bugs.webkit.org/show_bug.cgi?id=71673

        Reviewed by Zoltan Herczeg.

        Add another minimal testcase using <object> embedding SVGs + zooming.

        * platform/qt/Skipped: Unskip zoom-img-preserveAspectRatio-support-1.html.
        * platform/mac/svg/zoom/page/zoom-svg-as-object-expected.png: Added.
        * platform/mac/svg/zoom/page/zoom-svg-as-object-expected.txt: Added.
        * svg/zoom/page/resources/zoom-svg-as-object.svg: Added.
        * svg/zoom/page/zoom-svg-as-object.html: Added.

2011-11-11  Nikolas Zimmermann  <nzimmermann@rim.com>

        Zooming in SVGs in <object> is flakey
        https://bugs.webkit.org/show_bug.cgi?id=71673

        Reviewed by Zoltan Herczeg.

        It turns out zooming in SVGs in <object> wasn't flakey in Safari at all, only in DRT/Mac. In Safari it failed 100% reproducable.
        Scrollbars would always appear when zooming in a HTML document, containing an embedded SVG by <object>/<embed>/<iframe>, even
        though the content would visually fit perfectly, also it zoomed properly. Reloading would make the scrollbars disappear again.

        If scrollbars should be created for a FrameView or not, is determined by ScrollView::updateScrollbars(), by comparing the 
        visible size of the scroll view against the contents size. The contents size is propagated to the ScrollView, by
        FrameView::adjustViewSize(), which is called during FrameView::layout(). The size thats propagated is RenderView::documentRect().
        RenderView::documentRect() returns a writing-mode aware layoutOverflowRect(), computed by RenderBox::layoutOverflowRectForPropagation.

        If overflow is "visible", layoutOverflowRect() will return a union of the borderBoxRect() and the layoutOverflowRect(), which
        may exceed the visible size of the RenderView. For standalone SVG documents, the default value for the outermost <svg> renderer is
        "visible". When embedding SVGs through <object>s into a host document, the same code path is taken, and RenderView::documentRect()
        of the embedded SVG document will always return a union of the borderBoxREct() and the layoutOverflowRect().

        If that happens while zooming in a HTML document containing a SVG by <object>, scrollbars are created.
        By ensuring that overflow is treated as hidden, which is what Opera does (and makes sense!) this can't happen.

        The fix is to treat embedded SVGs as they would carry overflow="hidden" on the outermost <svg> renderer. That also makes
        sense as the embedded SVG cant paint outside an external "frame rect" thats given by the FrameView, effectively rendering
        as overflow "hidden" already.

        The fix is realized, by altering the overflow x/y values that are used in FrameView::applyOverflowToViewport(). Previously
        we never called that method for SVG, which was fine. Now we always call applyOverflowToViewport(), but only do something
        if the FrameView of the SVG is embedded in another document. If so, we force overflow to hidden.

        That fixes all zooming+<object> related flakiness seen on the chromium bots, most noticeable, without other side effects.
        All svg/overflow tests, still work as expected.

        Test: svg/zoom/page/zoom-svg-as-object.html

        * page/Frame.cpp:
        (WebCore::Frame::setPageAndTextZoomFactors): Remove unnecessary setNeedsLayout() call in SVG builds.
        * page/FrameView.cpp:
        (WebCore::FrameView::applyOverflowToViewport): Always enforce overflow=hidden, when embedding SVGs through object/embed/iframe.
                                                       Otherwise scrollbars will appear, even though the contents would fit without them.
        (WebCore::FrameView::calculateScrollbarModesForLayout): Always call applyOverflowToViewport, even for RenderSVGRoot. It only has
                                                                an effect though, when the FrameView of the SVG is embedded through <object>/etc.
        (WebCore::FrameView::layout): Remove unnecessary setChildNeedsLayout() call.
        * rendering/svg/RenderSVGRoot.cpp:
        (WebCore::RenderSVGRoot::isEmbeddedThroughFrameContainingSVGDocument): Fix this function, its meaning was reversed before!
        (WebCore::RenderSVGRoot::computeReplacedLogicalWidth): Fix logical error, by negating the result of isEmbeddedThroughFrameContainingSVGDocument.
        (WebCore::RenderSVGRoot::computeReplacedLogicalHeight): Ditto.
        * rendering/svg/RenderSVGRoot.h: Expose isEmbeddedThroughFrameContainingSVGDocument.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@99937 268f45cc-cd09-0410-ab3c-d52691b4dbfc