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 82 matching lines @@
     DEFINE_ATTRIBUTE_EVENT_LISTENER(touchcancel);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(touchend);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(touchmove);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(touchstart);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(webkitfullscreenchange);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(webkitfullscreenerror);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(wheel);
 
     bool hasAttribute(const QualifiedName&) const;
     const AtomicString& getAttribute(const QualifiedName&) const;
+
+    // Passing nullAtom as the second parameter removes the attribute when calling either of these set methods.
     void setAttribute(const QualifiedName&, const AtomicString& value);
     void setSynchronizedLazyAttribute(const QualifiedName&, const AtomicString& value);
+
     void removeAttribute(const QualifiedName&);
 
     // Typed getters and setters for language bindings.
     int getIntegralAttribute(const QualifiedName& attributeName) const;
     void setIntegralAttribute(const QualifiedName& attributeName, int value);
     unsigned getUnsignedIntegralAttribute(const QualifiedName& attributeName) const;
     void setUnsignedIntegralAttribute(const QualifiedName& attributeName, unsigned value);
     double getFloatingPointAttribute(const QualifiedName& attributeName, double fallbackValue = std::numeric_limits<double>::quiet_NaN()) const;
     void setFloatingPointAttribute(const QualifiedName& attributeName, double value);
 
@@ skipping 409 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 350 matching lines @@
 }
 
 inline bool isShadowHost(const Element* element)
 {
     return element && element->shadow();
 }
 
 } // namespace
 
 #endif