Fix crossorigin script module test assertions

The module/crossorigin.html WPT previously expected different behavior
when a "crossorigin" attribute was present on the script element vs
when it was missing. But that is incorrect per-spec. Updated the test
to expect the script load to be blocked in both cases.

BUG=594639

Review-Url: https://codereview.chromium.org/2914273002
Cr-Commit-Position: refs/heads/master@{#476655}
4 files changed