Initial implementation of display list backed 2D canvases

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 8f6029648c98e1d63d3950ddd6878ee2bc8f46fc..6ebc4aabe44decbd967dc0f228cdc0a32695ee20 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -48,6 +48,7 @@
 #include "platform/graphics/Canvas2DImageBufferSurface.h"
 #include "platform/graphics/GraphicsContextStateSaver.h"
 #include "platform/graphics/ImageBuffer.h"
+#include "platform/graphics/RecordingImageBufferSurface.h"
 #include "platform/graphics/UnacceleratedImageBufferSurface.h"
 #include "platform/graphics/gpu/WebGLImageBufferSurface.h"
 #include "platform/transforms/AffineTransform.h"
@@ -444,6 +445,12 @@ PassOwnPtr<ImageBufferSurface> HTMLCanvasElement::createImageBufferSurface(const
     if (is3D())
         return adoptPtr(new WebGLImageBufferSurface(size(), opacityMode));
 
+    if (document().settings() && document().settings()->displayList2dCanvasEnabled()) {
+        OwnPtr<ImageBufferSurface> surface = adoptPtr(new RecordingImageBufferSurface(size(), opacityMode));
+        if (surface->isValid())
+            return surface.release();
+    }
+
     if (shouldAccelerate(deviceSize)) {
         if (document().settings())
             *msaaSampleCount = document().settings()->accelerated2dCanvasMSAASampleCount();