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

Source/core/page/scrolling/ScrollingCoordinator.cpp

Index: Source/core/page/scrolling/ScrollingCoordinator.cpp
diff --git a/Source/core/page/scrolling/ScrollingCoordinator.cpp b/Source/core/page/scrolling/ScrollingCoordinator.cpp
index 0c078331c2d9287e3f5eff978a2183e92a6e74a2..a6369ddefabc667a09e125e1b1f8c6beaff4628f 100644
--- a/Source/core/page/scrolling/ScrollingCoordinator.cpp
+++ b/Source/core/page/scrolling/ScrollingCoordinator.cpp
@@ -396,8 +396,9 @@ static void makeLayerChildFrameMap(const Frame* currentFrame, LayerFrameMap* map
         const RenderLayer* containingLayer = child->ownerRenderer()->enclosingLayer();
         LayerFrameMap::iterator iter = map->find(containingLayer);
         if (iter == map->end())
-            iter = map->add(containingLayer, Vector<const Frame*>()).iterator;
-        iter->value.append(child);
+            map->add(containingLayer, Vector<const Frame*>()).iterator->value.append(child);
+        else
+            iter->value.append(child);
     }
 }
 
@@ -431,8 +432,11 @@ static void convertLayerRectsToEnclosingCompositedLayerRecursive(
         }
 
         LayerHitTestRects::iterator compIter = compositorRects.find(compositedLayer);
+        Vector<LayoutRect>* compIterValue;
         if (compIter == compositorRects.end())
-            compIter = compositorRects.add(compositedLayer, Vector<LayoutRect>()).iterator;
+            compIterValue = &compositorRects.add(compositedLayer, Vector<LayoutRect>()).iterator->value;
+        else
+            compIterValue = &compIter->value;
         // Transform each rect to the co-ordinate space of it's enclosing composited layer.
         for (size_t i = 0; i < layerIter->value.size(); ++i) {
             LayoutRect rect = layerIter->value[i];
@@ -445,7 +449,7 @@ static void convertLayerRectsToEnclosingCompositedLayerRecursive(
                 if (compositedLayer->renderer()->hasOverflowClip())
                     rect.move(compositedLayer->renderBox()->scrolledContentOffset());
             }
-            compIter->value.append(rect);
+            compIterValue->append(rect);
         }
     }