Fix flaky src= integration test on IE/Edge
Fix flaky src= integration test on IE/Edge

For some reason, on Edge and IE, starting this particular piece of
content at time 5 results in playback beginning at 4.9.  It could be
that the number is rounded to a keyframe or something.

This changes the test to expect the start time to be within 200ms of
the requested start time.

Change-Id: I5399a1eaf8a84b57a88359db2584f043e4a11e81

shaka-project/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,shaka-project/shaka-player,tvoli/shaka-player,tvoli/shaka-player