Pages are missing invalidations

Source/core/rendering/RenderObject.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 1500 matching lines @@
     if (!fullRepaint) {
         // This ASSERT fails due to animations.  See https://bugs.webkit.org/show_bug.cgi?id=37048
         // ASSERT(!newOutlineBoxRectPtr || *newOutlineBoxRectPtr == outlineBoundsForRepaint(repaintContainer));
         newOutlineBox = newOutlineBoxRectPtr ? *newOutlineBoxRectPtr : outlineBoundsForRepaint(repaintContainer);
 
         if ((hasOutline() && newOutlineBox.location() != oldOutlineBox.location())
             || (mustRepaintBackgroundOrBorder() && (newBounds != oldBounds || (hasOutline() && newOutlineBox != oldOutlineBox))))
             fullRepaint = true;
     }
 
-    // If there is no intersection between the old and the new bounds, invalidating
-    // the difference is more expensive than just doing a full repaint.
-    if (!fullRepaint && !newBounds.intersects(oldBounds))
+    // If we shifted, we don't know the exact reason so we are conservative and trigger a full invalidation. Shifting could
+    // be caused by some layout property (left / top) or some in-flow renderer inserted / removed before us in the tree.
+    if (!fullRepaint && newBounds.location() != oldBounds.location())
         fullRepaint = true;
 
     if (!repaintContainer)
         repaintContainer = v;
 
     if (fullRepaint) {
         repaintUsingContainer(repaintContainer, pixelSnappedIntRect(oldBounds));
         if (newBounds != oldBounds)
             repaintUsingContainer(repaintContainer, pixelSnappedIntRect(newBounds));
         return true;
@@ skipping 1874 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif