merge_pr_50590

Prevent choosing a font face labelled 'italic' when the style explicitly requested 'oblique'.

Differential Revision: https://phabricator.services.mozilla.com/D237194

bugzilla-url: https://bugzilla.mozilla.org/show_bug.cgi?id=1945642
gecko-commit: a3432e7f8a9775692c6945ab3438c1c46267d821
gecko-reviewers: dholbert