Replace character vectors with StringBuilders in the WebVTT tokenizer

Source/core/html/track/vtt/VTTTokenizer.h

 /*
  * 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 16 matching lines @@
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #ifndef VTTTokenizer_h
 #define VTTTokenizer_h
 
 #include "core/html/parser/InputStreamPreprocessor.h"
 #include "core/html/track/vtt/VTTToken.h"
 #include "wtf/PassOwnPtr.h"
+#include "wtf/text/StringBuilder.h"
 
 namespace WebCore {
 
 class VTTTokenizerState {
 public:
     enum State {
         DataState,
         EscapeState,
         TagState,
         StartTagState,
@@ skipping 47 matching lines @@
     VTTTokenizer();
 
     // m_token is owned by the caller. If nextToken is not on the stack,
     // this member might be pointing to unallocated memory.
     VTTToken* m_token;
 
     // This member does not really need to be an instance member - it's only used in nextToken.
     // The reason it's stored here is because of the use of the ADVANCE_TO state helpers.
     VTTTokenizerState::State m_state;
 
-    Vector<LChar, 32> m_buffer;
+    StringBuilder m_buffer;
 
     // ://www.whatwg.org/specs/web-apps/current-work/#preprocessing-the-input-stream
     InputStreamPreprocessor<VTTTokenizer> m_inputStreamPreprocessor;
 };
 
 }
 
 #endif