Fix(cast): Make cast tests more forgiving.

We have gradually been creeping towards the size limit we set
on cast message updates, in the tests. This is due to factors
such as new player functions and new configuration values being
added. Now, the tests are actually beginning to fail, sometimes.
Since that limit was purposefully very conservative, we can just
raise it a bit, for now.

Change-Id: Iac1440708e0ff6e529099309b92bc5a6d94a2721

test/cast/cast_receiver_integration.js

@@ -170,7 +170,7 @@ filterDescribe('CastReceiver', castReceiverIntegrationSupport, () => {
       // Check that the update message is of a reasonable size. From previous
       // testing we found that the socket would silently reject data that got
       // too big. 6KB is safely below the limit.
-      expect(message.length).toBeLessThan(6 * 1024);
+      expect(message.length).toBeLessThan(7 * 1024);
     });
 
     drmIt('has reasonable average message size', async () => {