(Concept patch) Simplify WTF::HashTable::add() return value for size and performance

Source/core/rendering/RenderObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved. (http://www.torchmobile.com/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2388 matching lines @@
     LayoutRect newContainerRect;
     computeSelfHitTestRects(ownRects, layerOffset);
 
     // When we get to have a lot of rects on a layer, the performance cost of tracking those
     // rects outweighs the benefit of doing compositor thread hit testing.
     // FIXME: This limit needs to be low due to the O(n^2) algorithm in
     // WebLayer::setTouchEventHandlerRegion - crbug.com/300282.
     const size_t maxRectsPerLayer = 100;
 
     LayerHitTestRects::iterator iter = layerRects.find(currentLayer);
+    Vector<WebCore::LayoutRect>* iterValue;
     if (iter == layerRects.end())
-        iter = layerRects.add(currentLayer, Vector<LayoutRect>()).iterator;
+        iterValue = &layerRects.add(currentLayer, Vector<LayoutRect>()).iterator->value;
+    else
+        iterValue = &iter->value;
     for (size_t i = 0; i < ownRects.size(); i++) {
         if (!containerRect.contains(ownRects[i])) {
-            iter->value.append(ownRects[i]);
-            if (iter->value.size() > maxRectsPerLayer) {
+            iterValue->append(ownRects[i]);
+            if (iterValue->size() > maxRectsPerLayer) {
                 // Just mark the entire layer instead, and switch to walking the layer
                 // tree instead of the render tree.
                 layerRects.remove(currentLayer);
                 currentLayer->addLayerHitTestRects(layerRects);
                 return;
             }
             if (newContainerRect.isEmpty())
                 newContainerRect = ownRects[i];
         }
     }
@@ skipping 960 matching lines @@
 {
     if (object1) {
         const WebCore::RenderObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showRenderTreeAndMark(object1, "*", object2, "-", 0);
     }
 }
 
 #endif