Set objects to need full paint invalidation after clearing their invalidation rects.

third_party/WebKit/Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1467 matching lines @@
 void LayoutObject::adjustPreviousPaintInvalidationForScrollIfNeeded(const DoubleSize& scrollDelta)
 {
     if (containerForPaintInvalidation().usesCompositedScrolling())
         return;
     m_previousPaintInvalidationRect.move(LayoutSize(scrollDelta));
 }
 
 void LayoutObject::clearPreviousPaintInvalidationRects()
 {
     setPreviousPaintInvalidationRect(LayoutRect());
+    // After clearing ("invalidating" the paint invalidation rects, mark this object as needing to re-compute them.
+    setShouldDoFullPaintInvalidation();
 }
 
 void LayoutObject::incrementallyInvalidatePaint(const LayoutBoxModelObject& paintInvalidationContainer, const LayoutRect& oldBounds, const LayoutRect& newBounds, const LayoutPoint& positionFromPaintInvalidationBacking)
 {
     ASSERT(oldBounds.location() == newBounds.location());
 
     LayoutUnit deltaRight = newBounds.maxX() - oldBounds.maxX();
     if (deltaRight > 0) {
         LayoutRect invalidationRect(oldBounds.maxX(), newBounds.y(), deltaRight, newBounds.height());
         invalidatePaintUsingContainer(paintInvalidationContainer, invalidationRect, PaintInvalidationIncremental);
@@ skipping 2152 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         WTFLogAlways("%s", "Cannot showLayoutTree. Root is (nil)");
     }
 }
 
 #endif