Oilpan: move 2D Canvas and WebGL objects to the heap.

Source/core/html/canvas/EXTBlendMinMax.h

 // 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.
 
 #ifndef EXTBlendMinMax_h
 #define EXTBlendMinMax_h
 
 #include "bindings/core/v8/ScriptWrappable.h"
 #include "core/html/canvas/WebGLExtension.h"
 #include "wtf/PassRefPtr.h"
 
 namespace blink {
 
 class EXTBlendMinMax FINAL : public WebGLExtension, public ScriptWrappable {
 public:
-    static PassRefPtr<EXTBlendMinMax> create(WebGLRenderingContextBase*);
+    static PassRefPtrWillBeRawPtr<EXTBlendMinMax> create(WebGLRenderingContextBase*);
     static bool supported(WebGLRenderingContextBase*);
     static const char* extensionName();
 
     virtual ~EXTBlendMinMax();
     virtual WebGLExtensionName name() const OVERRIDE;
 
 private:
-    EXTBlendMinMax(WebGLRenderingContextBase*);
+    explicit EXTBlendMinMax(WebGLRenderingContextBase*);
 };
 
 } // namespace blink
 
 #endif // EXTBlendMinMax_h