Use VTTScanner for VTT region settings parsing

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 42 matching lines @@
         (*position)++;
     return *position - startPosition;
 }
 
 unsigned VTTParser::collectDigitsToInt(const String& input, unsigned* position, int& number)
 {
     VTTLegacyScanner inputScanner(input, position);
     return inputScanner.scanDigits(number);
 }
 
-String VTTParser::collectWord(const String& input, unsigned* position)
-{
-    StringBuilder string;
-    while (*position < input.length() && !isASpace(input[*position]))
-        string.append(input[(*position)++]);
-    return string.toString();
-}
-
 bool VTTParser::parseFloatPercentageValue(const String& value, float& percentage)
 {
     // '%' must be present and at the end of the setting value.
     if (value.isEmpty() || value[value.length() - 1] != '%')
         return false;
 
     unsigned position = 0;
     unsigned digitsBeforeDot = scanDigits(value, &position);
     unsigned digitsAfterDot = 0;
     if (value[position] == '.') {
@@ skipping 508 matching lines @@
             m_currentNode->parserAppendChild(ProcessingInstruction::create(document, "timestamp", charactersString));
         break;
     }
     default:
         break;
     }
 }
 
 }