Standards Conformance Benchmarks
The scores in the Ecma test262 are identical on both operating systems, so the chart below is for both.
Opera takes the lead with a near-perfect score of 11 171 out of 11 181. Firefox places second, while Chrome finishes in third place. IE9's fourth-place score is a ways behind, but Safari is the definitive loser, achieving 10 397 points.
Chrome takes the lead in Windows with 374 points (plus 13 bonus points). Firefox places second, followed by Opera in third. Both browsers earn nine bonus points. Safari falls to a distant fourth place, while IE9 doesn't show well at all.
Chrome retains its lead in Ubuntu, though it drops 15 points behind its performance in Windows. The scores from Firefox and Opera do not change compared to what we say in Windows 7; they place second and third, respectively.
Peacekeeper HTML5 Capabilities
Chrome for Windows manages a perfect seven out of seven score in the HTML5 capabilities portion of Futuremark's Peacekeeper benchmark. Mozilla Firefox earns six out of seven points, putting it into second place. Chrome for Linux does as well, tying Firefox for first place in Ubuntu. Opera gets five points on both platforms, earning it third place in Windows and last in Linux. IE9 manages three out of seven, putting it in fourth place, while Safari suffers a last-place defeat.
Conformance Composite Grade
Since standards conformance testing always has a maximum and minimum score, we are able to assign overall standards conformance grades to each browser by converting each score to a maximum of 100 and averaging the results.
Chrome tops the chart in both operating systems. In Windows 7 it earns an A-, while its Linux version only achieves a B grade. Firefox achieves a solid B on both platforms. Opera barely gets a B-, putting it in third in both operating environments. IE9 and Safari each receive failing grades.