Reviewed by Dirk Schulze.

        All SVG *-expected.txt files contain wrong results
        https://bugs.webkit.org/show_bug.cgi?id=34703

        Finally dump meaningful information for SVG layout tests.
        Use 'absoluteClippedOverflowRect' which goes through the same code paths used
        to actually calculate repaint rects etc - instead of the legacy CSS-unaware
        code path that mapped 'repaintRectInLocalCoordinates' through 'absoluteTransform'.
        Remove absoluteTransform() - a long standing TODO, finally not needed anymore.

        Despite SVGRenderTreeAsText, SVGPaintServerGradient was also using absoluteTransform().
        Rewrite the code in question, fixing svg/W3C-SVG-1.1/pserver-grad-08-b.svg alignment issues
        when scaling/panning text using gradient on stroke/fill. Affects some other gradient tests as well.

        As we're now dumping clipped overflow rects any problems with repaint rects will become
        immediate visible - it turns out we're not supporting the overflow rules on the outermost <svg>
        element properly (repaint rects and bounding boxes need to take special SVG overflow rules into account).
        Fixing that magically gives pixel-perfect clipped overflow rects for all types of shapes/text/containers.

        Note: This will break any overriden platform-specific SVG results, need to wait for build bots in order to update them.

        * rendering/RenderObject.cpp: Remove absoluteTransform() method, centralize overflow query code in SVGRenderSupport::isOverflowHidden().
        * rendering/RenderObject.h: Remove absoluteTransform() method.
        * rendering/RenderSVGHiddenContainer.h: Ditto.
        * rendering/RenderSVGRoot.cpp:
        (WebCore::RenderSVGRoot::paint): Use SVGRenderSupport::isOverflowHidden() to query SVG overflow mode.
        (WebCore::RenderSVGRoot::computeRectForRepaint): Respect SVG overflow rules here: clip repaintRect against overflow rect _before_ passing
                                                         along to RenderBox. This is the key issue behind wrong absoluteClippedOverflowRect() values.
        (WebCore::RenderSVGRoot::nodeAtPoint): Use SVGRenderSupport::isOverflowHidden() to query SVG overflow mode.
        * rendering/RenderSVGRoot.h: Remove absoluteTransform(). Don't expose viewportSize() anymore.
        * rendering/RenderSVGText.cpp: 
        (WebCore::RenderSVGText::strokeBoundingBox): Fix default stroke width to 1. This was the only wrong place -> fixes repaint rects for stroked text.
        * rendering/RenderSVGViewportContainer.cpp: Remove absoluteTransform() method.
        (WebCore::RenderSVGViewportContainer::pointIsInsideViewportClip): Use SVGRenderSupport::isOverflowHidden() to query SVG overflow mode.
        * rendering/RenderSVGViewportContainer.h: Remove absoluteTransform() method.
        * rendering/SVGRenderSupport.cpp: Refactored overflow queries in one place, centralizing SVG specific assumptions about overflowX/Y.
        (WebCore::SVGRenderBase::isOverflowHidden):
        * rendering/SVGRenderSupport.h:
        * rendering/SVGRenderTreeAsText.cpp: Dump absoluteClippedOverflowRect() instead of absoluteTransform().mapRect(repaintRectInLocalCoordinates()).
        (WebCore::writePositionAndStyle): Affects all layout tests dumping render trees.
        * svg/graphics/SVGPaintServerGradient.cpp: Rewrite Gradient on text fill/stroke support on Cg, to avoid using absoluteTransform().
        (WebCore::absoluteTransformForRenderer):
        (WebCore::createMaskAndSwapContextForTextGradient):
        (WebCore::clipToTextMask):
        (WebCore::SVGPaintServerGradient::setup):


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@54483 268f45cc-cd09-0410-ab3c-d52691b4dbfc