Use the return value to signal success for VTTParser helpers

Source/core/html/track/vtt/VTTParser.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 77 matching lines @@
         return c == ' ' || c == '\t' || c == '\n' || c == '\f' || c == '\r';
     }
     static inline bool isValidSettingDelimiter(char c)
     {
         // ... a WebVTT cue consists of zero or more of the following components, in any order, separated from each other by one or more
         // U+0020 SPACE characters or U+0009 CHARACTER TABULATION (tab) characters.
         return c == ' ' || c == '\t';
     }
     static unsigned collectDigitsToInt(const String& input, unsigned* position, int& number);
     static String collectWord(const String&, unsigned*);
-    static double collectTimeStamp(const String&, unsigned*);
+    static bool collectTimeStamp(const String&, unsigned*, double& timeStamp);
 
     // Useful functions for parsing percentage settings.
-    static float parseFloatPercentageValue(const String&, bool&);
-    static FloatPoint parseFloatPercentageValuePair(const String&, char, bool&);
+    static bool parseFloatPercentageValue(const String&, float&);
+    static bool parseFloatPercentageValuePair(const String&, char, FloatPoint&);
 
     // Create the DocumentFragment representation of the WebVTT cue text.
     static PassRefPtr<DocumentFragment> createDocumentFragmentFromCueText(Document&, const String&);
 
     // Input data to the parser to parse.
     void parseBytes(const char* data, unsigned length);
     void flush();
 
     // Transfers ownership of last parsed cues to caller.
     void getNewCues(Vector<RefPtr<VTTCue> >&);
@@ skipping 33 matching lines @@
     VTTParserClient* m_client;
 
     Vector<RefPtr<VTTCue> > m_cuelist;
 
     Vector<RefPtr<VTTRegion> > m_regionList;
 };
 
 } // namespace WebCore
 
 #endif