New PaintController under-invalidation checking

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

 // Copyright 2015 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.
 
 #ifndef DisplayItemList_h
 #define DisplayItemList_h
 
 #include "platform/graphics/ContiguousContainer.h"
 #include "platform/graphics/paint/DisplayItem.h"
 #include "platform/graphics/paint/Transform3DDisplayItem.h"
@@ skipping 27 matching lines @@
     DisplayItemList& operator=(DisplayItemList&& source)
     {
         ContiguousContainer::operator=(std::move(source));
         m_visualRects = std::move(source.m_visualRects);
         m_beginItemIndices = std::move(source.m_beginItemIndices);
         return *this;
     }
 
     DisplayItem& appendByMoving(DisplayItem&);
 
+    bool hasVisualRect(unsigned index) const { return index < m_visualRects.size(); }
     IntRect visualRect(unsigned index) const
     {
-        ASSERT(index < m_visualRects.size());
+        DCHECK(hasVisualRect(index));
         return m_visualRects[index];
     }
 
     void appendVisualRect(const IntRect& visualRect);
 
     // Useful for iterating with a range-based for loop.
     template <typename Iterator>
     class Range {
     public:
         Range(const Iterator& begin, const Iterator& end)
@@ skipping 12 matching lines @@
     // given visual rect with the begin display item's visual rect.
     void growCurrentBeginItemVisualRect(const IntRect& visualRect);
 
     Vector<IntRect> m_visualRects;
     Vector<size_t> m_beginItemIndices;
 };
 
 } // namespace blink
 
 #endif // DisplayItemList_h