[webcrypto] Define the DOMException OperationError.

Source/core/dom/ExceptionCode.h

 /*
  *  Copyright (C) 2006, 2007 Apple Inc. All rights reserved.
  *
  *  This library is free software; you can redistribute it and/or
  *  modify it under the terms of the GNU Lesser General Public
  *  License as published by the Free Software Foundation; either
  *  version 2 of the License, or (at your option) any later version.
  *
  *  This library is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 60 matching lines @@
         VersionError,
 
         // File system
         NotReadableError,
         EncodingError,
         PathExistsError,
 
         // SQL
         SQLDatabaseError, // Naming conflict with DatabaseError class.
 
+        // Web Crypto
+        OperationError,
+
         // WebIDL exception types, handled by the binding layer.
         // FIXME: Add GeneralError, EvalError, etc. when implemented in the bindings.
         TypeError,
     };
 
 } // namespace WebCore
 
 #endif // ExceptionCode_h