fix wording to refer to "this content listener", r+sr=bz

uriloader/base/nsIURIContentListener.idl

@@ -74,7 +74,8 @@ interface nsIURIContentListener : nsISupports
   * @param aRequest             Request that is providing the data.
   * @param aContentHandler      nsIStreamListener that will consume the data.
   *                             This should be set to <code>nsnull</code> if
-  *                             no consumer can handle the content type.
+  *                             this content listener can't handle the content
+  *                             type.
   *
   * @return                     <code>true</code> if the consumer wants to
   *                             handle the load completely by itself.  This