The addition of unicode-plaintext to the pre element will make RTL text to appear from right to left. The html[dir] pre rule will make sure that this addition won't break the 'switch page direction' functionality.
MozReview-Commit-ID: 2JXJjqt2iuX
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extra : rebase_source : 98c85228ce50fa145bfaa77051532f69e92ba98d