IndexedDB: Rely on bindings for enum validation

Source/modules/indexeddb/IDBCursor.cpp

 /*
  * Copyright (C) 2010 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 341 matching lines @@
     return m_source->idbIndex()->objectStore();
 }
 
 bool IDBCursor::isDeleted() const
 {
     if (m_source->type() == IDBAny::IDBObjectStoreType)
         return m_source->idbObjectStore()->isDeleted();
     return m_source->idbIndex()->isDeleted();
 }
 
-WebIDBCursorDirection IDBCursor::stringToDirection(const String& directionString, ExceptionState& exceptionState)
+WebIDBCursorDirection IDBCursor::stringToDirection(const String& directionString)
 {
     if (directionString == IndexedDBNames::next)
         return WebIDBCursorDirectionNext;
     if (directionString == IndexedDBNames::nextunique)
         return WebIDBCursorDirectionNextNoDuplicate;
     if (directionString == IndexedDBNames::prev)
         return WebIDBCursorDirectionPrev;
     if (directionString == IndexedDBNames::prevunique)
         return WebIDBCursorDirectionPrevNoDuplicate;
 
-    exceptionState.throwTypeError("The direction provided ('" + directionString + "') is not one of 'next', 'nextunique', 'prev', or 'prevunique'.");
+    ASSERT_NOT_REACHED();
     return WebIDBCursorDirectionNext;
 }
 
 const String& IDBCursor::direction() const
 {
     switch (m_direction) {
     case WebIDBCursorDirectionNext:
         return IndexedDBNames::next;
 
     case WebIDBCursorDirectionNextNoDuplicate:
         return IndexedDBNames::nextunique;
 
     case WebIDBCursorDirectionPrev:
         return IndexedDBNames::prev;
 
     case WebIDBCursorDirectionPrevNoDuplicate:
         return IndexedDBNames::prevunique;
 
     default:
         ASSERT_NOT_REACHED();
         return IndexedDBNames::next;
     }
 }
 
 } // namespace blink