Implement 'will-change' parsing

Source/core/rendering/style/StyleWillChangeData.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 StyleWillChangeData_h
+#define StyleWillChangeData_h
+
+#include "CSSPropertyNames.h"
+#include "CSSValueKeywords.h"
+#include "wtf/PassRefPtr.h"
+#include "wtf/RefCounted.h"
+#include "wtf/Vector.h"
+
+namespace WebCore {
+
+class StyleWillChangeData : public RefCounted<StyleWillChangeData> {
+public:
+    static PassRefPtr<StyleWillChangeData> create() { return adoptRef(new StyleWillChangeData); }
+    PassRefPtr<StyleWillChangeData> copy() const { return adoptRef(new StyleWillChangeData(*this)); }
+
+    bool operator==(const StyleWillChangeData& o) const
+    {
+        return m_properties == o.m_properties && m_contents == o.m_contents && m_scrollPosition == o.m_scrollPosition;
+    }
+
+    bool operator!=(const StyleWillChangeData& o) const
+    {
+        return !(*this == o);
+    }
+
+    Vector<CSSPropertyID> m_properties;
+    unsigned m_contents : 1;
+    unsigned m_scrollPosition : 1;
+
+private:
+    StyleWillChangeData();
+    StyleWillChangeData(const StyleWillChangeData&);
+};
+
+} // namespace WebCore
+
+#endif // StyleWillChangeData_h