INPUT pattern attribute: Enable "unicode" flag.

third_party/WebKit/Source/bindings/core/v8/ScriptRegexp.h

 /*
  * Copyright (C) 2003, 2008, 2009 Apple Inc. All rights reserved.
  * Copyright (C) 2013 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
@@ skipping 35 matching lines @@
     enum CharacterMode {
         BMP, // NOLINT
         UTF16, // NOLINT
     };
 
     ScriptRegexp(const String&, TextCaseSensitivity, MultilineMode = MultilineDisabled, CharacterMode = BMP);
 
     int match(const String&, int startFrom = 0, int* matchLength = 0) const;
 
     bool isValid() const { return !m_regex.isEmpty(); }
+    // exceptionMessage is available only if !isValid().
+    String exceptionMessage() const { return m_exceptionMessage; }
 
 private:
     ScopedPersistent<v8::RegExp> m_regex;
+    String m_exceptionMessage;
 };
 
 } // namespace blink
 
 #endif // ScriptRegexp_h