Reland: 2D canvas: remain in deferred rendering mode with canvas to canvas drawImage

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 ba236832342b0382e851b15e55f70a98f2f5e158..0320ba40828fa735a203b2e9e19d25a7d1c53ba0 100644
--- a/Source/core/html/HTMLCanvasElement.cpp
+++ b/Source/core/html/HTMLCanvasElement.cpp
@@ -434,6 +434,11 @@ bool HTMLCanvasElement::is3D() const
     return m_context && m_context->is3d();
 }
 
+bool HTMLCanvasElement::isAnimated2D() const
+{
+    return m_context && m_context->is2d() && hasImageBuffer() && m_imageBuffer->wasDrawnToAfterSnapshot();
+}
+
 void HTMLCanvasElement::setSurfaceSize(const IntSize& size)
 {
     m_size = size;