[SPv2] Defer decision of raster invalidation after paint for changes z-index, transform, etc.

third_party/WebKit/Source/platform/graphics/paint/DisplayItemList.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/graphics/paint/DisplayItemList.h"
 
 #include "platform/graphics/paint/DrawingDisplayItem.h"
 #include "platform/graphics/paint/PaintChunk.h"
 #include "third_party/skia/include/core/SkPictureAnalyzer.h"
 
 #ifndef NDEBUG
 #include "wtf/text/WTFString.h"
 #endif
 
 namespace blink {
 
 DisplayItem& DisplayItemList::appendByMoving(DisplayItem& item)
 {
 #ifndef NDEBUG
     String originalDebugString = item.asDebugString();
 #endif
-    ASSERT(item.hasValidClient());
-    DisplayItem& result = ContiguousContainer::appendByMoving(item, item.derivedSize());
+    DCHECK(!item.hasBeenMoved());
+    DisplayItem& result = ContiguousContainer::appendByMoving(item, item.derivedSize(), size());
     // ContiguousContainer::appendByMoving() calls an in-place constructor
-    // on item which replaces it with a tombstone/"dead display item" that
-    // can be safely destructed but should never be used.
-    ASSERT(!item.hasValidClient());
+    // DisplayItem(size_t) to create a placeholder of type HasBeenMoved in
+    // place of the original item.
+    DCHECK(item.hasBeenMoved());
 #ifndef NDEBUG
     // Save original debug string in the old item to help debugging.
     item.setClientDebugString(originalDebugString);
 #endif
     return result;
 }
 
 void DisplayItemList::appendVisualRect(const IntRect& visualRect)
 {
     m_visualRects.append(visualRect);
 }
 
 DisplayItemList::Range<DisplayItemList::iterator>
 DisplayItemList::itemsInPaintChunk(const PaintChunk& paintChunk)
 {
     return Range<iterator>(begin() + paintChunk.beginIndex, begin() + paintChunk.endIndex);
 }
 
 DisplayItemList::Range<DisplayItemList::const_iterator>
 DisplayItemList::itemsInPaintChunk(const PaintChunk& paintChunk) const
 {
     return Range<const_iterator>(begin() + paintChunk.beginIndex, begin() + paintChunk.endIndex);
 }
 
 } // namespace blink