Revert event-mapper optimisations (#2171)

src/event-mapper.ts

@@ -29,21 +29,7 @@ export function eventMapperFor(client: MatrixClient, options: MapperOpts): Event
     const decrypt = options.decrypt !== false;
 
     function mapper(plainOldJsObject: Partial<IEvent>) {
-        const room = client.getRoom(plainOldJsObject.room_id);
-        let event: MatrixEvent;
-
-        // If the event is already known to the room, let's re-use the model
-        // rather than creating a duplicate
-        if (room) {
-            event = room.findEventById(plainOldJsObject.event_id);
-        }
-
-        // If no event is found or if the event found was only local we can
-        // safely create a new model
-        if (!event || event.status) {
-            event = new MatrixEvent(plainOldJsObject);
-        }
-
+        const event = new MatrixEvent(plainOldJsObject);
         if (event.isEncrypted()) {
             if (!preventReEmit) {
                 client.reEmitter.reEmit(event, [