Use C++11 features in core/html

Source/core/html/canvas/WebGLContextGroup.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 73 matching lines @@
         (*it)->detachContextGroup();
     }
 }
 
 void WebGLContextGroup::loseContextGroup(WebGLRenderingContextBase::LostContextMode mode, WebGLRenderingContextBase::AutoRecoveryMethod autoRecoveryMethod)
 {
     // Detach must happen before loseContextImpl, which destroys the GraphicsContext3D
     // and prevents groupObjects from being properly deleted.
     detachAndRemoveAllObjects();
 
-    for (HashSet<WebGLRenderingContextBase*>::iterator it = m_contexts.begin(); it != m_contexts.end(); ++it)
-        (*it)->loseContextImpl(mode, autoRecoveryMethod);
+    for (const auto& context : m_contexts)
+        context->loseContextImpl(mode, autoRecoveryMethod);
 }
 
 } // namespace blink