Use the correct method for computing a repaint rect that takes into account squashing.

Source/core/rendering/RenderLayerRepainter.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
  *   Randall Jesup <rjesup@wgate.com>
@@ skipping 90 matching lines @@
 void RenderLayerRepainter::clearRepaintRects()
 {
     ASSERT(!m_renderer.layer()->hasVisibleContent());
 
     m_repaintRect = IntRect();
 }
 
 void RenderLayerRepainter::computeRepaintRects()
 {
     const RenderLayerModelObject* repaintContainer = m_renderer.containerForRepaint();
+    LayoutRect repaintRect = m_renderer.boundsRectForRepaint(repaintContainer);
     if (RuntimeEnabledFeatures::repaintAfterLayoutEnabled()) {
         // FIXME: We want RenderLayerRepainter to go away when
         // repaint-after-layout is on by default so we need to figure out how to
         // handle this update.
-        m_renderer.setPreviousRepaintRect(m_renderer.computeRepaintRect());
+        m_renderer.setPreviousRepaintRect(repaintRect);
     } else {
-        m_repaintRect = m_renderer.computeRepaintRect();
+        m_repaintRect = repaintRect;
         m_offset = m_renderer.positionFromRepaintContainer(repaintContainer);
     }
 }
 
 void RenderLayerRepainter::computeRepaintRectsIncludingDescendants()
 {
     // FIXME: computeRepaintRects() has to walk up the parent chain for every layer to compute the rects.
     // We should make this more efficient.
     // FIXME: it's wrong to call this when layout is not up-to-date, which we do.
     computeRepaintRects();
@@ skipping 129 matching lines @@
 RenderLayer* RenderLayerRepainter::enclosingFilterRepaintLayer() const
 {
     for (const RenderLayer* curr = m_renderer.layer(); curr; curr = curr->parent()) {
         if ((curr != m_renderer.layer() && curr->requiresFullLayerImageForFilters()) || curr->compositingState() == PaintsIntoOwnBacking || curr->isRootLayer())
             return const_cast<RenderLayer*>(curr);
     }
     return 0;
 }
 
 } // Namespace WebCore