Reviewed by Darin Fisher.

        Hook the GLES2 rendering path up to GraphicsContextSkia.
        https://bugs.webkit.org/show_bug.cgi?id=43119
        
        This connects the state-setting and drawing calls implemented in
        so far in GLES2Canvas, and calls PlatformContextSkia's
        prepareForSoftwareDraw() for all the non-accelerated paths.

        * platform/graphics/skia/GraphicsContextSkia.cpp:
        (WebCore::GraphicsContext::addInnerRoundedRectClip):
        (WebCore::GraphicsContext::addPath):
        (WebCore::GraphicsContext::beginPath):
        (WebCore::GraphicsContext::clip):
        (WebCore::GraphicsContext::drawConvexPolygon):
        (WebCore::GraphicsContext::drawEllipse):
        (WebCore::GraphicsContext::drawFocusRing):
        (WebCore::GraphicsContext::drawLine):
        (WebCore::GraphicsContext::drawLineForMisspellingOrBadGrammar):
        (WebCore::GraphicsContext::drawLineForText):
        (WebCore::GraphicsContext::drawRect):
        (WebCore::GraphicsContext::fillPath):
        (WebCore::GraphicsContext::fillRoundedRect):
        (WebCore::GraphicsContext::strokeArc):
        (WebCore::GraphicsContext::strokePath):
        (WebCore::GraphicsContext::strokeRect):
        These calls are software-only; call preSoftwareDraw() for these.
        (WebCore::GraphicsContext::savePlatformState):
        (WebCore::GraphicsContext::restorePlatformState):
        (WebCore::GraphicsContext::setAlpha):
        (WebCore::GraphicsContext::setCompositeOperation):
        (WebCore::GraphicsContext::setPlatformFillColor):
        (WebCore::GraphicsContext::scale):
        (WebCore::GraphicsContext::rotate):
        (WebCore::GraphicsContext::translate):
        (WebCore::GraphicsContext::concatCTM):
        These ones set state on both Skia and GLES2Canvas.
        (WebCore::GraphicsContext::clearRect):
        (WebCore::GraphicsContext::fillRect):
        These ones have a GLES2 implementation; call through to it if PlatformContextSkia's useGPU() flag is set and the state permits.
        * platform/graphics/skia/PlatformContextSkia.cpp:
        (PlatformContextSkia::prepareForSoftwareDraw):
        (PlatformContextSkia::prepareForHardwareDraw):
        Rename preXXXDraw() -> prepareForXXXDraw().
        * platform/graphics/skia/PlatformContextSkia.h:
        (PlatformContextSkia::prepareForSoftwareDraw):
        (PlatformContextSkia::prepareForHardwareDraw):
        Rename preXXXDraw() -> prepareForXXXDraw().


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@64227 268f45cc-cd09-0410-ab3c-d52691b4dbfc