Removing the dependency on GraphicsContext for drawing images in 2D canvas

Source/core/html/HTMLCanvasElement.cpp

Index: Source/core/html/HTMLCanvasElement.cpp
diff --git a/Source/core/html/HTMLCanvasElement.cpp b/Source/core/html/HTMLCanvasElement.cpp
index 49710329fd8e816f698731528da41ff417d1bbb4..840378ef5edfd32b021a75dba70405aa8a0f58cd 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -289,7 +289,7 @@ void HTMLCanvasElement::didDraw(const FloatRect& rect)
     m_dirtyRect.unite(rect);
     if (m_context && m_context->is2d() && hasImageBuffer())
         buffer()->didDraw(rect);
-    notifyObserversCanvasChanged(m_dirtyRect);
+    notifyObserversCanvasChanged(rect);

[Stephen White, 2015/05/27 15:46:02]

Out of curiosity, is this a bugfix / optimization?

[Justin Novosad, 2015/05/27 20:08:16]

Drive-by optimization. We use to do these notification per frame instead of per
draw, but that led to sync issues. Before, when it was per frame, m_dirtyRect
was the right thing. This change probably won't make any significant difference
except in degenerate  cases of -webkit-canvas

 }
 
 void HTMLCanvasElement::didFinalizeFrame()
@@ -682,8 +682,6 @@ void HTMLCanvasElement::createImageBufferInternal(PassOwnPtr<ImageBufferSurface>
     }
 
     m_imageBuffer->setClient(this);
-    m_imageBuffer->context()->setShouldClampToSourceRect(false);
-    m_imageBuffer->context()->disableAntialiasingOptimizationForHairlineImages();
     m_imageBuffer->context()->setImageInterpolationQuality(CanvasDefaultInterpolationQuality);

[Stephen White, 2015/05/27 15:46:02]

Is this still used / necessary? If we're no longer using the GC, we should be
setting this on the new SkCanvas instead, no?

[Justin Novosad, 2015/05/27 20:08:16]

Acknowledged.

     // Enabling MSAA overrides a request to disable antialiasing. This is true regardless of whether the
     // rendering mode is accelerated or not. For consistency, we don't want to apply AA in accelerated