[wpt] Fix masked failure in display-mode.https.html
a. assert_true() checks for strict equality with true 0, so coerce
the MediaQueryList accordingly.
b. Failure (a) was not correctly attributed to the test because
step_func_done() expects sync functions that can throw 1. Passing
an async function will immediately mark the test as a success, but
the returned promise that eventually rejects isn't handled, causing
a harness error 2. The async_test() can be expressed more
naturally as a promise_test().
Bug: 41496375
Change-Id: I894678b014ffdbc69e3e8b4e766eccefc1a67043
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5868839
Commit-Queue: Jonathan Lee jonathanjlee@google.com
Reviewed-by: Fr beaufort.francois@gmail.com
Cr-Commit-Position: refs/heads/main@{#1356524}