1 Test WebSocket.extensions attribute.
3 On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
5 Check the value before opening the connection:
6 PASS ws.extensions is ""
7 Check if the value is read only:
8 PASS ws.extensions = 'foo'; ws.extensions is ""
9 Check the value after the connection is established:
10 PASS ws.extensions is "permessage-deflate"
11 Check the value of the Sec-WebSocket-Extensions header sent to the server:
12 PASS event.data is "permessage-deflate; client_max_window_bits, x-webkit-deflate-frame"
13 PASS successfullyParsed is true