289843 release references to the listener when the download is complete

r=bz sr=darin a=asa

embedding/components/webbrowserpersist/src/nsWebBrowserPersist.cpp

@@ -478,7 +478,7 @@ NS_IMETHODIMP nsWebBrowserPersist::SaveDocument(
     
     if (aOutputContentType)
     {
-        mContentType.AssignWithConversion(aOutputContentType);
+        mContentType.AssignASCII(aOutputContentType);
     }
 
     rv = SaveDocumentInternal(aDocument, fileAsURI, datapathAsURI);
@@ -780,6 +780,11 @@ NS_IMETHODIMP nsWebBrowserPersist::OnStopRequest(
         }
         mProgressListener->OnStateChange(nsnull, request, stateFlags, status);
     }
+    if (completed)
+    {
+        mProgressListener = nsnull;
+        mProgressListener2 = nsnull;
+    }
 
     return NS_OK;
 }