Reduce invalidation on children-needs-layout containers

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 598 matching lines @@
     // Not in the middle of layout so have to find the thread the slow way.
     RenderObject* curr = const_cast<RenderObject*>(this);
     while (curr) {
         if (curr->isRenderFlowThread())
             return toRenderFlowThread(curr);
         curr = curr->containingBlock();
     }
     return 0;
 }
 
+bool RenderObject::skipInvalidationWhenLaidOutChildren() const
+{
+    if (!neededLayoutBecauseOfChildren())
+        return false;
+
+    // SVG renderers need to be invalidated when their children are laid out.
+    // RenderBlocks with line boxes are responsible to invalidate them so we can't ignore them.
+    if (isSVG() || (isRenderBlock() && toRenderBlock(this)->firstLineBox()))
+        return false;
+
+    return rendererHasNoBoxEffect();
+}
+
 RenderBlock* RenderObject::firstLineBlock() const
 {
     return 0;
 }
 
 static inline bool objectIsRelayoutBoundary(const RenderObject* object)
 {
     // FIXME: In future it may be possible to broaden these conditions in order to improve performance.
     if (object->isTextControl())
         return true;
@@ skipping 2868 matching lines @@
 bool RenderObject::isRelayoutBoundaryForInspector() const
 {
     return objectIsRelayoutBoundary(this);
 }
 
 void RenderObject::clearPaintInvalidationState()
 {
     setShouldDoFullPaintInvalidationAfterLayout(false);
     setShouldDoFullPaintInvalidationIfSelfPaintingLayer(false);
     setOnlyNeededPositionedMovementLayout(false);
+    setNeededLayoutBecauseOfChildren(false);
     setShouldInvalidateOverflowForPaint(false);
     setLayoutDidGetCalled(false);
     setMayNeedPaintInvalidation(false);
 }
 
 bool RenderObject::isAllowedToModifyRenderTreeStructure(Document& document)
 {
     return DeprecatedDisableModifyRenderTreeStructureAsserts::canModifyRenderTreeStateInAnyState()
         || document.lifecycle().stateAllowsRenderTreeMutations();
 }
@@ skipping 33 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif