[Typed-OM] Add compound type of CSSVariableReferenceValue and String with some tests

third_party/WebKit/Source/core/css/cssom/CSSTokenStreamValue.cpp

 // Copyright 2016 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.
 
 #include "core/css/cssom/CSSTokenStreamValue.h"
 
 #include "core/css/CSSVariableReferenceValue.h"
+#include "core/css/cssom/CSSStyleVariableReferenceValue.h"
 #include "core/css/parser/CSSTokenizer.h"
 #include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
 namespace {
 
 class TokenStreamValueIterationSource final : public ValueIterable<StringOrCSSVariableReferenceValue>::IterationSource {
 public:
     explicit TokenStreamValueIterationSource(CSSTokenStreamValue* tokenStreamValue)
         : m_tokenStreamValue(tokenStreamValue)
     {
     }
 
     bool next(ScriptState*, StringOrCSSVariableReferenceValue& value, ExceptionState&) override
     {
         if (m_index >= m_tokenStreamValue->size())
             return false;
-        value.setString(m_tokenStreamValue->fragmentAtIndex(m_index));
+        value = m_tokenStreamValue->fragmentAtIndex(m_index);
         return true;
     }
 
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
         visitor->trace(m_tokenStreamValue);
         ValueIterable<StringOrCSSVariableReferenceValue>::IterationSource::trace(visitor);
     }
 
 private:
     const Member<CSSTokenStreamValue> m_tokenStreamValue;
 };
 
 } // namespace
 
 ValueIterable<StringOrCSSVariableReferenceValue>::IterationSource* CSSTokenStreamValue::startIteration(ScriptState*, ExceptionState&)
 {
     return new TokenStreamValueIterationSource(this);
 }
 
 CSSValue* CSSTokenStreamValue::toCSSValue() const
 {
     StringBuilder tokens;
 
     for (unsigned i = 0; i < m_fragments.size(); i++) {
         if (i)
             tokens.append("/**/");
-        tokens.append(m_fragments[i]);
+        if (m_fragments[i].isString())
+            tokens.append(m_fragments[i].getAsString());
+        else if (m_fragments[i].isCSSVariableReferenceValue())
+            tokens.append(m_fragments[i].getAsCSSVariableReferenceValue()->variable());
+        else
+            NOTREACHED();
     }
 
     CSSTokenizer::Scope scope(tokens.toString());
 
     return CSSVariableReferenceValue::create(CSSVariableData::create(scope.tokenRange()));
 }
 
 } // namespace blink