Bug 1486358 - Mark GetTransactionAtIndex() as NS_IMETHODIMP. r=me

Because of one this bug's earlier commits made it an XPIDL method.

--HG--
extra : rebase_source : d0e69d5c5eb1fd1caf0946872c8319029591fcc3

docshell/shistory/nsSHistory.cpp

@@ -727,7 +727,7 @@ nsSHistory::GetEntryAtIndex(int32_t aIndex, bool aModifyIndex,
 }
 
 /* Get the transaction at a given index */
-nsresult
+NS_IMETHODIMP
 nsSHistory::GetTransactionAtIndex(int32_t aIndex, nsISHTransaction** aResult)
 {
   NS_ENSURE_ARG_POINTER(aResult);