Use Shadow DOM to display fallback content for images

Source/core/html/HTMLImageFallbackHelper.h

Index: Source/core/html/HTMLImageFallbackHelper.h
diff --git a/Source/core/html/HTMLMenuElement.h b/Source/core/html/HTMLImageFallbackHelper.h
similarity index 67%
copy from Source/core/html/HTMLMenuElement.h
copy to Source/core/html/HTMLImageFallbackHelper.h
index a5f8a81a812d3bc8e9262f3ccfb1a232974d2886..cd2fa4a168299ee1d58556446e0b867e8cae2277 100644
--- a/Source/core/html/HTMLMenuElement.h
+++ b/Source/core/html/HTMLImageFallbackHelper.h
@@ -1,7 +1,5 @@
 /*

[pdr., 2014/11/14 07:34:17]

For new files the lawyercats have asked that we just use the small copyright
header (http://www.chromium.org/developers/coding-style#TOC-File-headers)

// 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.

(Here, and HTMLImageFallbackHelper.cpp)

- * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
- *           (C) 1999 Antti Koivisto (koivisto@kde.org)
- * Copyright (C) 2010 Apple Inc. All rights reserved.
+ * Copyright (C) 2014 Robert Hogan <robhogan@chromium.org>.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
@@ -20,22 +18,22 @@
  *
  */
 
-#ifndef HTMLMenuElement_h
-#define HTMLMenuElement_h
+#ifndef HTMLImageFallbackHelper_h
+#define HTMLImageFallbackHelper_h
 
-#include "core/html/HTMLElement.h"
+#include "wtf/PassRefPtr.h"
 
 namespace blink {
 
-class HTMLMenuElement final : public HTMLElement {
-    DEFINE_WRAPPERTYPEINFO();
-public:
-    DECLARE_NODE_FACTORY(HTMLMenuElement);
+class Element;
+class RenderStyle;
 
-private:
-    explicit HTMLMenuElement(Document&);
+class HTMLImageFallbackHelper {
+public:
+    static void createAltTextShadowTree(Element&);
+    static PassRefPtr<RenderStyle> customStyleForAltText(Element&, PassRefPtr<RenderStyle> newStyle);
 };
 
 } // namespace blink
 
-#endif // HTMLMenuElement_h
+#endif // HTMLImageFallbackHelper_h