Reviewed by Kenneth Russell.

        [CHROMIUM] Assert w/canvas image draw
        https://bugs.webkit.org/show_bug.cgi?id=44279

        Don't use bitmap->pixelRef()->getPixels() directly; prefer
        bitmap->pixels() and an SkAutoLockPixels.  Also, make sure to set
        the backing store state to Software when it was None.  This handles
        missing draws when the first call is software.  Finally, remove some
        spurious prepareForSoftwareDraw() calls in addPath() and beginPath().
        It's really the fillPath() or strokePath() that matters.

        Covered by LayoutTests/fast/canvas/arc360.html and others.

        * platform/graphics/skia/GraphicsContextSkia.cpp:
        (WebCore::GraphicsContext::addPath):
        (WebCore::GraphicsContext::beginPath):
        Remove spurious prepareForSoftwareDraw() calls.
        * platform/graphics/skia/ImageSkia.cpp:
        (WebCore::drawBitmapGLES2):
        Lock SkBitmap's pixels, and use ->getPixels().
        * platform/graphics/skia/PlatformContextSkia.cpp:
        (WebCore::PlatformContextSkia::prepareForSoftwareDraw):
        Switch backing store state to Software when it was None.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@65700 268f45cc-cd09-0410-ab3c-d52691b4dbfc