Reviewed by Kenneth Russell.

        [chromium] Force canvas 2d draw calls to happen in software if a gradient, pattern, shadow, or clip are active
        https://bugs.webkit.org/show_bug.cgi?id=45405

        This forces all draw calls to happen in software instead of hardware if there is a fill pattern, gradient,
        shadow, or clip applied; at least until we can handle these in hardware.  Otherwise the pattern/gradient/etc
        is completely ignored by the hardware drawing routine and we render incorrectly.

        The test is slightly convervative - for example it will force drawImage() calls to happen in software if a
        fill gradient is set even though it's irrelevant.  This doesn't seem to be an issue in practice and we
        can tighten the checks later if needed.

        Tested by fast/canvas/canvas-incremental-repaint.html.

        * platform/graphics/skia/GraphicsContextSkia.cpp:
        (WebCore::GraphicsContext::canvasClip):
        (WebCore::GraphicsContext::fillRect):
        * platform/graphics/skia/ImageBufferSkia.cpp:
        (WebCore::ImageBuffer::draw):
        * platform/graphics/skia/ImageSkia.cpp:
        (WebCore::BitmapImage::draw):
        (WebCore::BitmapImageSingleFrameSkia::draw):
        * platform/graphics/skia/PlatformContextSkia.cpp:
        (WebCore::PlatformContextSkia::State::State):
        (WebCore::PlatformContextSkia::canvasClipPath):
        (WebCore::PlatformContextSkia::canAccelerate):
        * platform/graphics/skia/PlatformContextSkia.h:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@67003 268f45cc-cd09-0410-ab3c-d52691b4dbfc