The test is failing on Windows, Linux, and Mac. http://test-results.appspot.com/dashboards/flakiness_dashboard.html#tests=fast%2Fforms%2Finput-number-unacceptable-style.html&showExpectations=true&showLargeExpectations=true&group=%40ToT%20-%20chromium.org It looks "-1a" is recognized as a valid number. I'm investigating this issue.
Fixed by http://trac.webkit.org/changeset/80105