input[type=number] UI should reject invalid characters.

Source/platform/text/PlatformLocale.h

 /*
  * Copyright (C) 2012 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:
  * 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 41 matching lines @@
     String convertToLocalizedNumber(const String&);
 
     // Converts the specified localized number string to a number string in the
     // HTML floating-point number format. The input string is provided by a end
     // user, and might not be a number string. It's ok that the function returns
     // a string which is not conforms to the HTML floating-point number format,
     // callers of this function are responsible to check the format of the
     // resultant string.
     String convertFromLocalizedNumber(const String&);
 
+    // Remove characters from |input| if a character is not included in
+    // locale-specific number characters and |standardChars|.
+    String stripInvalidNumberCharacters(const String& input, const String& standardChars) const;
+
 #if ENABLE(INPUT_MULTIPLE_FIELDS_UI)
     // Returns localized decimal separator, e.g. "." for English, "," for French.
     String localizedDecimalSeparator();
 #endif
 
     // Returns date format in Unicode TR35 LDML[1] containing day of month,
     // month, and year, e.g. "dd/mm/yyyy"
     // [1] LDML http://unicode.org/reports/tr35/#Date_Format_Patterns
     virtual String dateFormat() = 0;
 
@@ skipping 83 matching lines @@
 
 private:
     bool detectSignAndGetDigitRange(const String& input, bool& isNegative, unsigned& startIndex, unsigned& endIndex);
     unsigned matchedDecimalSymbolIndex(const String& input, unsigned& position);
 
     String m_decimalSymbols[DecimalSymbolsSize];
     String m_positivePrefix;
     String m_positiveSuffix;
     String m_negativePrefix;
     String m_negativeSuffix;
+    String m_acceptableNumberCharacters;
     bool m_hasLocaleData;
 };
 
 } // namespace blink
 #endif