Print out "null" in this case instead of the unhelpful
"${expected}". Update the wpt version as well.

Update test expectations appropriately.

Bug: 706826
Test:
Change-Id: I99466a5891d1902d4e516c2824cae481bd5c7fdb
Reviewed-on: https://chromium-review.googlesource.com/769293
Reviewed-by: Hongchan Choi <[email protected]>
Commit-Queue: Raymond Toy <[email protected]>
Cr-Commit-Position: refs/heads/master@{#516407}