Pass through watchlist state to response data

This got lost when the watchlist updating code was refactored
out into controller.js, as it assumes that 'data' (the post data)
is still available.

Bug: T261362
Change-Id: Id274e7b8518b62dddbc3d4095d9f6cab17aa17cd

modules/CommentController.js

@@ -307,6 +307,8 @@ CommentController.prototype.save = function ( comment, pageName ) {
 			}
 			return $.Deferred().reject( code, responseData ).promise();
 		} ).then( function ( responseData ) {
+			// Pass through watchlist state.
+			responseData.watchlist = data.watchlist;
 			controller.update( responseData, comment, pageName, replyWidget );
 		} );
 	} );