WebVTT: Support fractional percentage values for position/line/size

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

 /*
  * Copyright (c) 2013, Opera Software ASA. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 111 matching lines @@
 
     // Scan a set of ASCII digits from the input. Return the number of digits
     // scanned, and set |number| to the computed value. If the digits make up a
     // number that does not fit the 'int' type, |number| is set to INT_MAX.
     // Note: Does not handle sign.
     unsigned scanDigits(int& number);
 
     // Scan a floating point value on one of the forms: \d+\.? \d+\.\d+ \.\d+
     bool scanFloat(float& number);
 
+    // Scan a floating point value (per scanFloat) followed by a '%'.
+    bool scanPercentage(float& percentage);
+
 protected:
     Position position() const { return m_data.characters8; }
     Position end() const { return m_end.characters8; }
     void seekTo(Position);
     UChar currentChar() const;
     void advance(unsigned amount = 1);
     // Adapt a UChar-predicate to an LChar-predicate.
     // (For use with skipWhile/Until from ParsingUtilities.h).
     template<bool characterPredicate(UChar)>
     static inline bool LCharPredicateAdapter(LChar c) { return characterPredicate(c); }
@@ skipping 82 matching lines @@
     ASSERT(position() < end());
     if (m_is8Bit)
         m_data.characters8 += amount;
     else
         m_data.characters16 += amount;
 }
 
 }
 
 #endif