RAL: Eliminate n^2 walk to find repaint containers

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 106 matching lines @@
     return false;
 }
 
 // The SVG addFocusRingRects() method adds rects in local coordinates so the default absoluteFocusRingQuads
 // returns incorrect values for SVG objects. Overriding this method provides access to the absolute bounds.
 void RenderSVGModelObject::absoluteFocusRingQuads(Vector<FloatQuad>& quads)
 {
     quads.append(localToAbsoluteQuad(FloatQuad(repaintRectInLocalCoordinates())));
 }
 
-void RenderSVGModelObject::repaintTreeAfterLayout()
+void RenderSVGModelObject::repaintTreeAfterLayout(RenderLayerModelObject& repaintContainer)

[Julien - ping for review, 2014/05/07 17:50:03]

This should be a const RenderLayerModelObject& as we shouldn't be modifying
repaintContainer anywhere in the logic.

 {
     // Note: This is a reduced version of RenderBox::repaintTreeAfterLayout().
     // FIXME: Should share code with RenderBox::repaintTreeAfterLayout().
     LayoutStateDisabler layoutStateDisabler(*this);
 
     ASSERT(RuntimeEnabledFeatures::repaintAfterLayoutEnabled());
     ASSERT(!needsLayout());
 
     const LayoutRect oldRepaintRect = previousRepaintRect();
     const LayoutPoint oldPositionFromRepaintContainer = previousPositionFromRepaintContainer();
-    RenderLayerModelObject* repaintContainer = containerForRepaint();
-    setPreviousRepaintRect(clippedOverflowRectForRepaint(repaintContainer));
-    setPreviousPositionFromRepaintContainer(positionFromRepaintContainer(repaintContainer));
+    RenderLayerModelObject& newRepaintContainer = *containerForRepaint();
+    setPreviousRepaintRect(clippedOverflowRectForRepaint(&newRepaintContainer));
+    setPreviousPositionFromRepaintContainer(positionFromRepaintContainer(&newRepaintContainer));

[Julien - ping for review, 2014/05/07 17:50:03]

It really looks like clippedOverflowrectForRepaint and
positionFromRepaintContainer should take reference as they don't expect a NULL
repaintContainer. This can be done in this change or in a follow-up.

[leviw_travelin_and_unemployed, 2014/05/07 17:58:48]

There's one exception to this. absoluteClippedOverflowRect passes null to denote
"absolute," but it should be fixed to return the view it wants to translate
into.

 
     // If we are set to do a full repaint that means the RenderView will be
     // invalidated. We can then skip issuing of invalidations for the child
     // renderers as they'll be covered by the RenderView.
     if (view()->doingFullRepaint()) {
-        RenderObject::repaintTreeAfterLayout();
+        RenderObject::repaintTreeAfterLayout(newRepaintContainer);
         return;
     }
 
     const LayoutRect& newRepaintRect = previousRepaintRect();
     const LayoutPoint& newPositionFromRepaintContainer = previousPositionFromRepaintContainer();
     repaintAfterLayoutIfNeeded(containerForRepaint(),
         shouldDoFullRepaintAfterLayout(), oldRepaintRect, oldPositionFromRepaintContainer, &newRepaintRect, &newPositionFromRepaintContainer);
 
-    RenderObject::repaintTreeAfterLayout();
+    RenderObject::repaintTreeAfterLayout(newRepaintContainer);
 }
 
 } // namespace WebCore