Update StyleValue.cssString() to use existing methods instead of rolling our own.

third_party/WebKit/Source/core/css/cssom/LengthValue.h

 // Copyright 2015 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 LengthValue_h
 #define LengthValue_h
 
 #include "core/css/cssom/StyleValue.h"
 
 namespace blink {
@@ skipping 32 matching lines @@
     static LengthValue* parse(const String& cssString, ExceptionState&);
     static LengthValue* fromValue(double value, const String& typeStr, ExceptionState&);
     static LengthValue* fromDictionary(const CalcDictionary&, ExceptionState&);
 
     LengthValue* clone();
 
 protected:
     LengthValue() {}
 
     static LengthUnit lengthUnitFromName(const String&);
-    static const String& lengthTypeToString(LengthUnit type);
+    static const String& lengthTypeToString(LengthUnit);
+    static CSSPrimitiveValue::UnitType lengthTypeToPrimitiveType(LengthUnit);
 
     virtual LengthValue* addInternal(const LengthValue* other, ExceptionState&);
     virtual LengthValue* subtractInternal(const LengthValue* other, ExceptionState&);
     virtual LengthValue* multiplyInternal(double, ExceptionState&);
     virtual LengthValue* divideInternal(double, ExceptionState&);
 };
 
 } // namespace blink
 
 #endif