Clear mutable inline style when it is empty.

Source/core/dom/Element.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2013 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
@@ skipping 513 matching lines @@
     bool hasActiveAnimations() const;
 
     InputMethodContext* inputMethodContext();
     bool hasInputMethodContext() const;
 
     virtual void setPrefix(const AtomicString&, ExceptionState&) OVERRIDE FINAL;
 
     void synchronizeAttribute(const AtomicString& localName) const;
 
     MutableStylePropertySet* ensureMutableInlineStyle();
+    void clearMutableInlineStyleIfEmpty();
 
 protected:
     Element(const QualifiedName& tagName, Document* document, ConstructionType type)
         : ContainerNode(document, type)
         , m_tagName(tagName)
     {
         ScriptWrappable::init(this);
     }
 
     void addPropertyToPresentationAttributeStyle(MutableStylePropertySet*, CSSPropertyID, CSSValueID identifier);
@@ skipping 29 matching lines @@
     // classAttributeChanged() exists to share code between
     // parseAttribute (called via setAttribute()) and
     // svgAttributeChanged (called when element.className.baseValue is set)
     void classAttributeChanged(const AtomicString& newClassString);
 
     PassRefPtr<RenderStyle> originalStyleForRenderer();
 
     Node* insertAdjacent(const String& where, Node* newChild, ExceptionState&);
 
 private:
+    void removeSynchronizedLazyAttribute(const QualifiedName&);
+
     void styleAttributeChanged(const AtomicString& newStyleString, AttributeModificationReason);
 
     void updatePresentationAttributeStyle();
 
     void inlineStyleChanged();
     PropertySetCSSStyleDeclaration* inlineStyleCSSOMWrapper();
     void setInlineStyleFromString(const AtomicString&);
 
     StyleRecalcChange recalcOwnStyle(StyleRecalcChange);
     void recalcChildStyle(StyleRecalcChange);
@@ skipping 301 matching lines @@
 }
 
 inline bool isShadowHost(const Element* element)
 {
     return element && element->shadow();
 }
 
 } // namespace
 
 #endif