Bug 1886328 - Port bug 1356686 change to nsIStreamConverter.idl. r=leftmostcat

Port of c58710d55a

Differential Revision: https://phabricator.services.mozilla.com/D205161

--HG--
extra : moz-landing-system : lando

mailnews/mime/src/nsStreamConverter.cpp

@@ -943,6 +943,11 @@ NS_IMETHODIMP nsStreamConverter::FirePendingStartRequest() {
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsStreamConverter::MaybeRetarget(nsIRequest* request) {
+  return NS_ERROR_NOT_IMPLEMENTED;
+}
+
 NS_IMETHODIMP nsStreamConverter::GetConvertedType(const nsACString& aFromType,
                                                   nsIChannel* aChannel,
                                                   nsACString& aToType) {