Show debug information for invalid display items

Source/platform/graphics/ContiguousContainer.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 ContiguousContainer_h
 #define ContiguousContainer_h
 
 #include "platform/PlatformExport.h"
 #include "wtf/Alignment.h"
 #include "wtf/Compiler.h"
@@ skipping 158 matching lines @@
 
     void swap(ContiguousContainer& other) { ContiguousContainerBase::swap(other); }
 
     // Appends a new element using memcpy, then default-constructs a base
     // element in its place. Use with care.
     BaseElementType& appendByMoving(BaseElementType& item, size_t size)
     {
         ASSERT(size >= sizeof(BaseElementType));
         void* newItem = allocate(size);
         memcpy(newItem, static_cast<void*>(&item), size);
-        new (&item) BaseElementType;
+        new (&item) BaseElementType(
+#ifndef NDEBUG
+            item.asDebugString()
+#endif
+        );
         return *static_cast<BaseElementType*>(newItem);
     }
 
 private:
     static size_t align(size_t size)
     {
         size_t alignedSize = alignment * ((size + alignment - 1) / alignment);
         ASSERT(alignedSize % alignment == 0);
         ASSERT(alignedSize >= size);
         ASSERT(alignedSize < size + alignment);
         return alignedSize;
     }
 };
 
 } // namespace blink
 
 #endif // ContiguousContainer_h