Enforce clearing renderers' paint invalidation state

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 3377 matching lines @@
     return false;
 }
 
 bool RenderObject::isRelayoutBoundaryForInspector() const
 {
     return objectIsRelayoutBoundary(this);
 }
 
 void RenderObject::clearPaintInvalidationState()
 {
+    // paintInvalidationStateIsDirty should be kept in sync with the
+    // booleans that are cleared below.
+    ASSERT(paintInvalidationStateIsDirty());

[dsinclair, 2014/07/11 20:48:55]

Is this needed? We're basically checking that we never clear the state of a
renderer that wasn't dirty?

[Julien - ping for review, 2014/07/11 20:52:46]

It's here for 2 reasons:
- Ensure that clearPaintInvalidationState and paintInvalidationStateIsDirty stay
in sync.
- Make sure we don't call this function on renderers that don't need it (and we
don't :)). We have seen with SVG that tree walks can be expensive so I think
it's a good ASSERT to have.

+
     setShouldDoFullPaintInvalidationAfterLayout(false);
     setShouldDoFullPaintInvalidationIfSelfPaintingLayer(false);
     setOnlyNeededPositionedMovementLayout(false);
     setNeededLayoutBecauseOfChildren(false);
     setShouldInvalidateOverflowForPaint(false);
     setLayoutDidGetCalled(false);
     setMayNeedPaintInvalidation(false);
 }
 
 bool RenderObject::isAllowedToModifyRenderTreeStructure(Document& document)
@@ skipping 37 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif