Turn VTTToken into an immutable object

Source/core/html/track/vtt/VTTParser.cpp

 /*
  * Copyright (C) 2011 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 368 matching lines @@
     RefPtr<DocumentFragment> fragment = DocumentFragment::create(m_document);
 
     if (cueText.isEmpty()) {
         fragment->parserAppendChild(Text::create(m_document, ""));
         return fragment;
     }
 
     m_currentNode = fragment;
 
     VTTTokenizer tokenizer(cueText);
-    m_token.clear();
     m_languageStack.clear();
 
     while (tokenizer.nextToken(m_token))
         constructTreeFromToken(m_document);
 
     return fragment.release();
 }
 
 PassRefPtr<DocumentFragment> VTTParser::createDocumentFragmentFromCueText(Document& document, const String& cueText)
 {
@@ skipping 131 matching lines @@
     }
     return VTTNodeTypeNone;
 }
 
 void VTTTreeBuilder::constructTreeFromToken(Document& document)
 {
     // http://dev.w3.org/html5/webvtt/#webvtt-cue-text-dom-construction-rules
 
     switch (m_token.type()) {
     case VTTTokenTypes::Character: {
-        String content = m_token.characters().toString();
-        RefPtr<Text> child = Text::create(document, content);
+        RefPtr<Text> child = Text::create(document, m_token.characters());
         m_currentNode->parserAppendChild(child);
         break;
     }
     case VTTTokenTypes::StartTag: {
         RefPtr<VTTElement> child;
         VTTNodeType nodeType = tokenToNodeType(m_token);
         if (nodeType != VTTNodeTypeNone)
             child = VTTElement::create(nodeType, &document);
         if (child) {
             if (!m_token.classes().isEmpty())
-                child->setAttribute(classAttr, m_token.classes().toAtomicString());
+                child->setAttribute(classAttr, m_token.classes());
 
             if (child->webVTTNodeType() == VTTNodeTypeVoice) {
-                child->setAttribute(VTTElement::voiceAttributeName(), m_token.annotation().toAtomicString());
+                child->setAttribute(VTTElement::voiceAttributeName(), m_token.annotation());
             } else if (child->webVTTNodeType() == VTTNodeTypeLanguage) {
-                m_languageStack.append(m_token.annotation().toAtomicString());
+                m_languageStack.append(m_token.annotation());
                 child->setAttribute(VTTElement::langAttributeName(), m_languageStack.last());
             }
             if (!m_languageStack.isEmpty())
                 child->setLanguage(m_languageStack.last());
             m_currentNode->parserAppendChild(child);
             m_currentNode = child;
         }
         break;
     }
     case VTTTokenTypes::EndTag: {
         VTTNodeType nodeType = tokenToNodeType(m_token);
         if (nodeType != VTTNodeTypeNone) {
             if (nodeType == VTTNodeTypeLanguage && m_currentNode->isVTTElement() && toVTTElement(m_currentNode.get())->webVTTNodeType() == VTTNodeTypeLanguage)
                 m_languageStack.removeLast();
             if (m_currentNode->parentNode())
                 m_currentNode = m_currentNode->parentNode();
         }
         break;
     }
     case VTTTokenTypes::TimestampTag: {
         unsigned position = 0;
-        String charactersString = m_token.characters().toString();
+        String charactersString = m_token.characters();
         double time = VTTParser::collectTimeStamp(charactersString, &position);
         if (time != malformedTime)
             m_currentNode->parserAppendChild(ProcessingInstruction::create(document, "timestamp", charactersString));
         break;
     }
     default:
         break;
     }
-    m_token.clear();
 }
 
 void VTTParser::skipWhiteSpace(const String& line, unsigned* position)
 {
     while (*position < line.length() && isASpace(line[*position]))
         (*position)++;
 }
 
 }