Ensure proper finalization of garbage-collected types.

Source/core/css/CSSCalculationValue.h

 /*
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 39 matching lines @@
 enum CalculationCategory {
     CalcNumber = 0,
     CalcLength,
     CalcPercent,
     CalcPercentNumber,
     CalcPercentLength,
     CalcOther
 };
 
 class CSSCalcExpressionNode : public RefCountedWillBeGarbageCollected<CSSCalcExpressionNode> {
+    DECLARE_EMPTY_VIRTUAL_DESTRUCTOR_WILL_BE_REMOVED(CSSCalcExpressionNode);
 public:
     enum Type {
         CssCalcPrimitiveValue = 1,
         CssCalcBinaryOperation
     };
 
-    virtual ~CSSCalcExpressionNode() = 0;
     virtual bool isZero() const = 0;
     virtual PassOwnPtr<CalcExpressionNode> toCalcValue(const CSSToLengthConversionData&) const = 0;
     virtual double doubleValue() const = 0;
     virtual double computeLengthPx(const CSSToLengthConversionData&) const = 0;
     virtual String customCSSText() const = 0;
     virtual bool equals(const CSSCalcExpressionNode& other) const { return m_category == other.m_category && m_isInteger == other.m_isInteger; }
     virtual Type type() const = 0;
 
     CalculationCategory category() const { return m_category; }
     virtual CSSPrimitiveValue::UnitTypes primitiveType() const = 0;
@@ skipping 59 matching lines @@
     const RefPtrWillBeMember<CSSCalcExpressionNode> m_expression;
     const bool m_nonNegative;
 };
 
 DEFINE_CSS_VALUE_TYPE_CASTS(CSSCalcValue, isCalcValue());
 
 } // namespace WebCore
 
 
 #endif // CSSCalculationValue_h