[Gecko Bug 1878347] Allow global=window-module

[moz-wptsync-bot]

Implements https://github.com/web-platform-tests/rfcs/pull/133.

Differential Revision: https://phabricator.services.mozilla.com/D200470

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1878347 gecko-commit: 400fd14b708738816caa78c5be9bec9f9aaf4705 gecko-reviewers: jgraham