rooms is a proper collection now, so no need for getter on session

src/matrix/session.js

@@ -42,10 +42,6 @@ export default class Session {
         return this._rooms;
     }
 
-	getRoom(roomId) {
-		return this._rooms.get(roomId);
-	}
-
 	createRoom(roomId) {
 		const room = new Room(roomId, this._storage, this._roomUpdateCallback);
 		this._rooms.add(roomId, room);

src/matrix/sync.js

@@ -82,7 +82,7 @@ export default class Sync extends EventEmitter {
 			// presence
 			if (response.rooms) {
 				parseRooms(response.rooms, (roomId, roomResponse, membership) => {
-					let room = this._session.getRoom(roomId);
+					let room = this._session.rooms.get(roomId);
 					if (!room) {
 						room = this._session.createRoom(roomId);
 					}