merge_pr_48276
Make CSS zoom apply to themed widgets properly.
Differential Revision: https://phabricator.services.mozilla.com/D222320
bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1918838
gecko-commit: 4b595e1843aa64b05f111f363838f3adea239f3a
gecko-reviewers: dshin