Rework float value/percentage scanning for VTTRegion

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 108 matching lines @@
     // Return a String constructed from the rest of the input (between input
     // pointer and end of input), and advance the input pointer accordingly.
     String restOfInputAsString();
 
     // 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+

[Mike West, 2014/01/21 07:59:24]

Is "0." a valid floating point value? It doesn't seem like it should be, but
maybe there's a good reason for that strangeness?

[fs, 2014/01/21 08:19:57]

It is a valid floating point value. (Compare to other definitions - like C++
[2.13.3]).

+    bool scanFloat(float& number);
+
 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 115 matching lines @@
     unsigned* m_outPosition;
     union {
         const LChar* characters8;
         const UChar* characters16;
     } m_start;
 };
 
 }
 
 #endif