[RAL] Reduce SVG tree walks

Source/core/rendering/svg/RenderSVGModelObject.cpp

 /*
  * Copyright (c) 2009, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 124 matching lines @@
         return;
 
     LayoutStateDisabler layoutStateDisabler(*this);
 
     const LayoutRect oldPaintInvalidationRect = previousPaintInvalidationRect();
     const LayoutPoint oldPositionFromPaintInvalidationContainer = previousPositionFromPaintInvalidationContainer();
     const RenderLayerModelObject& newPaintInvalidationContainer = *containerForRepaint();
     setPreviousPaintInvalidationRect(clippedOverflowRectForRepaint(&newPaintInvalidationContainer));
     setPreviousPositionFromPaintInvalidationContainer(positionFromRepaintContainer(&newPaintInvalidationContainer));
 
+    // If an ancestor container had its transform changed, then we just
+    // need to update the RenderSVGModelObject's repaint rect above. The invalidation
+    // will be handled by the container where the transform changed. This essentially
+    // means that we prune the entire branch for performance.
+    if (!SVGRenderSupport::parentTransformDidChange(this))
+        return;
+
     // If we are set to do a full paint invalidation that means the RenderView will be
     // issue paint invalidations. We can then skip issuing of paint invalidations for the child
     // renderers as they'll be covered by the RenderView.
     if (view()->doingFullRepaint()) {
         RenderObject::invalidateTreeAfterLayout(newPaintInvalidationContainer);
         return;
     }
 
     const LayoutRect& newPaintInvalidationRect = previousPaintInvalidationRect();
     const LayoutPoint& newPositionFromPaintInvalidationContainer = previousPositionFromPaintInvalidationContainer();
     repaintAfterLayoutIfNeeded(containerForRepaint(),
         shouldDoFullPaintInvalidationAfterLayout(), oldPaintInvalidationRect, oldPositionFromPaintInvalidationContainer,
         &newPaintInvalidationRect, &newPositionFromPaintInvalidationContainer);
 
     RenderObject::invalidateTreeAfterLayout(newPaintInvalidationContainer);
 }
 
 } // namespace WebCore