Clear mutable inline style when it is empty.

Source/core/css/VariablesIterator.h

 /*
  * Copyright (C) 2013 Google 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
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #ifndef VariablesIterator_h
 #define VariablesIterator_h
 
 #include "core/css/CSSVariablesIterator.h"
 #include "wtf/Vector.h"
 #include "wtf/text/AtomicString.h"
 
 namespace WebCore {
 
 class MutableStylePropertySet;
+class StylePropertySet;
 
 class AbstractVariablesIterator : public CSSVariablesIterator {
 public:
     virtual ~AbstractVariablesIterator() { }
 
 protected:
     void takeRemainingNames(Vector<AtomicString>& remainingNames) { m_remainingNames.swap(remainingNames); }
 
+    virtual void initRemainingNames(const StylePropertySet*);
+
 private:
     virtual void advance() OVERRIDE;
     virtual bool atEnd() const OVERRIDE { return m_remainingNames.isEmpty(); }
     virtual AtomicString name() const OVERRIDE { return m_remainingNames.last(); }
     virtual String value() const OVERRIDE;
     virtual void addedVariable(const AtomicString& name) OVERRIDE;
     virtual void removedVariable(const AtomicString& name) OVERRIDE;
     virtual void clearedVariables() OVERRIDE;
 
     virtual MutableStylePropertySet* propertySet() const = 0;
 
     Vector<AtomicString> m_remainingNames;
     Vector<AtomicString> m_newNames;
 };
 
 class VariablesIterator : public AbstractVariablesIterator {
 public:
     static PassRefPtr<VariablesIterator> create(MutableStylePropertySet*);
 
 private:
-    explicit VariablesIterator(MutableStylePropertySet* propertySet) : m_propertySet(propertySet) { }
-
+    explicit VariablesIterator(MutableStylePropertySet*);
     virtual MutableStylePropertySet* propertySet() const OVERRIDE { return m_propertySet.get(); }
 
     RefPtr<MutableStylePropertySet> m_propertySet;
 };
 
 } // namespace WebCore
 
 #endif // VariablesIterator_h