... but falls short on HTML5 test
IE9 scored 135 out of 400 on a test to determine support for the HTML5 standard. On my Windows 7 computer, Firefox scored 159 and Chrome led the way with 301. Caveat: The test seems to indicate what percentage of HTML5 features each browser supports, but not the functionality of each supported feature. The test does not cover all HTML5 features, either.