Track scissored damage area for WebGL

Source/core/rendering/compositing/CompositedLayerMapping.cpp

Index: Source/core/rendering/compositing/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/compositing/CompositedLayerMapping.cpp b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
index 1019a447bae2cc7c86ae0202b8b43b2709879cfa..23b1c00aba7b174adb71b4deb97a35a5a43c30a5 100644
--- a/Source/core/rendering/compositing/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
@@ -1830,7 +1830,7 @@ bool CompositedLayerMapping::isDirectlyCompositedImage() const
     return false;
 }
 
-void CompositedLayerMapping::contentChanged(ContentChangeType changeType)
+void CompositedLayerMapping::contentChanged(ContentChangeType changeType, const IntRect& dirtyRect)
 {
     if ((changeType == ImageChanged) && renderer()->isImage() && isDirectlyCompositedImage()) {
         updateImageContents();
@@ -1838,7 +1838,7 @@ void CompositedLayerMapping::contentChanged(ContentChangeType changeType)
     }
 
     if (changeType == CanvasChanged && isAcceleratedCanvas(renderer())) {
-        m_graphicsLayer->setContentsNeedsDisplay();
+        m_graphicsLayer->setContentsNeedsDisplay(dirtyRect);
         return;
     }
 }