Use C++11 range-based loop for core/css

Source/core/css/CSSCrossfadeValue.cpp

Index: Source/core/css/CSSCrossfadeValue.cpp
diff --git a/Source/core/css/CSSCrossfadeValue.cpp b/Source/core/css/CSSCrossfadeValue.cpp
index 1b41d7f282f558aa24add07a73c8b27805a50bdb..b2a7e004e6dd40b474b436343fb7019db40881b3 100644
--- a/Source/core/css/CSSCrossfadeValue.cpp
+++ b/Source/core/css/CSSCrossfadeValue.cpp
@@ -189,9 +189,8 @@ PassRefPtr<Image> CSSCrossfadeValue::image(RenderObject* renderer, const IntSize
 
 void CSSCrossfadeValue::crossfadeChanged(const IntRect&)
 {
-    RenderObjectSizeCountMap::const_iterator end = clients().end();
-    for (RenderObjectSizeCountMap::const_iterator curr = clients().begin(); curr != end; ++curr) {
-        RenderObject* client = const_cast<RenderObject*>(curr->key);
+    for (const auto& curr : clients()) {
+        RenderObject* client = const_cast<RenderObject*>(curr.key);
         client->imageChanged(static_cast<WrappedImagePtr>(this));
     }
 }