Deflake NetworkingEngine unit tests
Deflake NetworkingEngine unit tests

These tests were a little flaky on Edge.

Rather than just adding a small delay to cover Promise resolution, now
we wait for the actual Promise, then add a small delay to cover the
setting of the status member.

Change-Id: I7462d3b308afd59ea036d6b0ec0ddfd4a87c71bc

shaka-project/shaka-player,baconz/shaka-player,indiereign/shaka-player,cmgrecu/shaka-player,ustudio/shaka-player,TheModMaker/shaka-player,cmgrecu/shaka-player,vimond/shaka-player,vimond/shaka-player,indiereign/shaka-player,brightcove/shaka-player,ustudio/shaka-player,Ross-cz/shaka-player,TheModMaker/shaka-player,shaka-project/shaka-player,TheModMaker/shaka-player,indiereign/shaka-player,baconz/shaka-player,TheModMaker/shaka-player,TobbeEdgeware/shaka-player,baconz/shaka-player,russitto/shaka-player,russitto/shaka-player,russitto/shaka-player,ustudio/shaka-player,shaka-project/shaka-player,shaka-project/shaka-player,brightcove/shaka-player,brightcove/shaka-player,tvoli/shaka-player,Ross-cz/shaka-player,TobbeEdgeware/shaka-player,ustudio/shaka-player,tvoli/shaka-player,Ross-cz/shaka-player,vimond/shaka-player,TobbeEdgeware/shaka-player,tvoli/shaka-player,cmgrecu/shaka-player,tvoli/shaka-player