Remove stale TODO about calling elementAt

Source/platform/graphics/paint/DisplayItemList.cpp

 // Copyright 2014 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 "config.h"
 #include "platform/graphics/paint/DisplayItemList.h"
 
 #include "platform/NotImplemented.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/TraceEvent.h"
@@ skipping 129 matching lines @@
 }
 
 size_t DisplayItemList::findMatchingItemFromIndex(const DisplayItem::Id& id, const DisplayItemIndicesByClientMap& displayItemIndicesByClient, const DisplayItems& list)
 {
     DisplayItemIndicesByClientMap::const_iterator it = displayItemIndicesByClient.find(id.client);
     if (it == displayItemIndicesByClient.end())
         return kNotFound;
 
     const Vector<size_t>& indices = it->value;
     for (size_t index : indices) {
-        // TODO(pdr): elementAt is not cheap so this should be refactored (See crbug.com/505965).
         const DisplayItem& existingItem = list[index];
         ASSERT(!existingItem.isValid() || existingItem.client() == id.client);
         if (existingItem.isValid() && id.matches(existingItem))
             return index;
     }
 
     return kNotFound;
 }
 
 void DisplayItemList::addItemToIndexIfNeeded(const DisplayItem& displayItem, size_t index, DisplayItemIndicesByClientMap& displayItemIndicesByClient)
@@ skipping 385 matching lines @@
 
 void DisplayItemList::replay(GraphicsContext& context)
 {
     TRACE_EVENT0("blink,benchmark", "DisplayItemList::replay");
     ASSERT(m_newDisplayItems.isEmpty());
     for (DisplayItem& displayItem : m_currentDisplayItems)
         displayItem.replay(context);
 }
 
 } // namespace blink