Add support for CSSValue->CSSSimpleLength when it is a percentage.

third_party/WebKit/Source/core/css/cssom/CSSSimpleLength.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 CSSSimpleLength_h
 #define CSSSimpleLength_h
 
 #include "core/css/cssom/CSSLengthValue.h"
 
 namespace blink {
 
 class CSSPrimitiveValue;
 class ExceptionState;
 
 class CORE_EXPORT CSSSimpleLength final : public CSSLengthValue {
     WTF_MAKE_NONCOPYABLE(CSSSimpleLength);
     DEFINE_WRAPPERTYPEINFO();
 public:
     static CSSSimpleLength* create(double, const String& type, ExceptionState&);
     static CSSSimpleLength* create(double value, CSSPrimitiveValue::UnitType type)
     {
         return new CSSSimpleLength(value, type);
     }
     static CSSSimpleLength* fromCSSValue(const CSSPrimitiveValue&);
 
     bool containsPercent() const override;
 
     double value() const { return m_value; }
-    String unit() const { return String(CSSPrimitiveValue::unitTypeToString(m_unit)); }
+    String unit() const;
     CSSPrimitiveValue::UnitType lengthUnit() const { return m_unit; }
 
     StyleValueType type() const override { return StyleValueType::SimpleLengthType; }
 
     CSSValue* toCSSValue() const override;
 
 protected:
     virtual CSSLengthValue* addInternal(const CSSLengthValue* other);
     virtual CSSLengthValue* subtractInternal(const CSSLengthValue* other);
     virtual CSSLengthValue* multiplyInternal(double);
@@ skipping 10 matching lines @@
     DEFINE_TYPE_CASTS(CSSSimpleLength, argumentType, value, \
         value->type() == CSSLengthValue::StyleValueType::SimpleLengthType, \
         value.type() == CSSLengthValue::StyleValueType::SimpleLengthType)
 
 DEFINE_SIMPLE_LENGTH_TYPE_CASTS(CSSLengthValue);
 DEFINE_SIMPLE_LENGTH_TYPE_CASTS(CSSStyleValue);
 
 } // namespace blink
 
 #endif