Fix ExceptionState with empty context.

Source/bindings/v8/ExceptionState.cpp

 /*
  * 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:
  *
  *     * 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 29 matching lines @@
 void ExceptionState::clearException()
 {
     m_code = 0;
     m_exception.clear();
 }
 
 void ExceptionState::throwDOMException(const ExceptionCode& ec, const String& message)
 {
     ASSERT(ec);
     ASSERT(m_isolate);
+    ASSERT(!m_creationContext.IsEmpty());
 
     // SecurityError is thrown via ::throwSecurityError, and _careful_ consideration must be given to the data exposed to JavaScript via the 'sanitizedMessage'.
     ASSERT(ec != SecurityError);
 
     m_code = ec;
     String processedMessage = addExceptionContext(message);
     m_message = processedMessage;
     setException(V8ThrowException::createDOMException(ec, processedMessage, m_creationContext, m_isolate));
 }
 
 void ExceptionState::throwSecurityError(const String& sanitizedMessage, const String& unsanitizedMessage)
 {
     ASSERT(m_isolate);
+    ASSERT(!m_creationContext.IsEmpty());
     m_code = SecurityError;
     String finalSanitized = addExceptionContext(sanitizedMessage);
     m_message = finalSanitized;
     String finalUnsanitized = addExceptionContext(unsanitizedMessage);
 
     setException(V8ThrowException::createDOMException(SecurityError, finalSanitized, finalUnsanitized, m_creationContext, m_isolate));
 }
 
 void ExceptionState::setException(v8::Handle<v8::Value> exception)
 {
@@ skipping 83 matching lines @@
             processedMessage = ExceptionMessages::failedToDeleteIndexed(interfaceName(), message);
         else if (m_context == IndexedGetterContext)
             processedMessage = ExceptionMessages::failedToGetIndexed(interfaceName(), message);
         else if (m_context == IndexedSetterContext)
             processedMessage = ExceptionMessages::failedToSetIndexed(interfaceName(), message);
     }
     return processedMessage;
 }
 
 } // namespace WebCore