Add the picture element

Source/core/html/HTMLPictureElement.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 HTMLPictureElement_h
+#define HTMLPictureElement_h
+
+#include "core/html/HTMLElement.h"
+
+namespace WebCore {
+
+class HTMLPictureElement FINAL : public HTMLElement {
+public:
+    static PassRefPtr<HTMLPictureElement> create(Document&);
+
+protected:
+    explicit HTMLPictureElement(Document&);
+};
+
+} // namespace
+
+#endif