Failing promise_setup() in a worker never issues results.

[dalecurtis]

Specifically this will hang in a worker:

// META: global=window,dedicatedworker

promise_setup(async () => {
  assert_implements_optional(false, 'platform unsupported');
});

promise_test(t => {
  return Promise.resolve('yay!');
});

... but when run from a window:

This is a testharness.js-based test.
Harness Error. harness_status.status = 1 , harness_status.message = Error: platform unsupported
NOTRUN broken
Harness: the test ran to completion.

I tried to trace through what's going wrong, but got lost. My best guess is that results are never sent to the window's message port, so even though complete is sent nothing ends up displayed.