Revert of Verify paintedOutputOfObjectHasNoEffectRegardlessOfSize during painting

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

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 1291 matching lines @@
   LayoutRect invalidatePaintRectangle(const LayoutRect&,
                                       DisplayItemClient* = nullptr) const;
 
   // Walk the tree after layout issuing paint invalidations for layoutObjects
   // that have changed or moved, updating bounds that have changed, and clearing
   // paint invalidation state.
   virtual void invalidateTreeIfNeeded(const PaintInvalidationState&);
 
   void setShouldDoFullPaintInvalidationIncludingNonCompositingDescendants();
 
+  // Returns true if the object itself will not generate any effective painted
+  // output no matter what size the object is. For example, this function can
+  // return false for an object whose size is currently 0x0 but would have
+  // effective painted output if it was set a non-empty size.
+  // It's used to skip unforced paint invalidation (which is when
+  // shouldDoFullPaintInvalidation is false, but mayNeedPaintInvalidation or
+  // childShouldCheckForPaintInvalidation is true) to avoid unnecessary paint
+  // invalidations of empty areas covered by such objects.
+  virtual bool paintedOutputOfObjectHasNoEffectRegardlessOfSize() const {
+    return false;
+  }
+
   // Returns the rect that should have paint invalidated whenever this object
   // changes. The rect is in the view's coordinate space. This method deals with
   // outlines and overflow.
   virtual LayoutRect absoluteVisualRect() const;
 
   // Returns the rect that should have paint invalidated whenever this object
   // changes. The rect is in the object's local coordinate space. This is for
   // non-SVG objects and LayoutSVGRoot only. SVG objects (except LayoutSVGRoot)
   // should use visualRectInLocalSVGCoordinates() and map with SVG transforms
   // instead.
@@ skipping 1328 matching lines @@
 CORE_EXPORT void showLineTree(const blink::LayoutObject*);
 CORE_EXPORT void showLayoutTree(const blink::LayoutObject* object1);
 // We don't make object2 an optional parameter so that showLayoutTree
 // can be called from gdb easily.
 CORE_EXPORT void showLayoutTree(const blink::LayoutObject* object1,
                                 const blink::LayoutObject* object2);
 
 #endif
 
 #endif  // LayoutObject_h