When setting same value (including empty to empty), some browsers might not turn off undo. If settings non-empty value, all browsers doesn't turn off undo. Also, if empty value, Edge and Chrome doesn't turn off undo.
MozReview-Commit-ID: 1nVYEzBr5KJ
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extra : rebase_source : e49f38e7c5a8f69902d6320eb6740e34e3f161ed
Makoto Kato