Firefox 12.0a1 (2012-01-17) outputs "matrix(1, 0, 0, 1, 0px, 0px)". All other browsers (IE9, Chrome 17 dev, Opera Next 12.00 alpha) omit the "px" part. See <https://www.w3.org/Bugs/Public/show_bug.cgi?id=15431>. Other browsers omit the "px", of course, because they don't support it (bug 719054, <https://www.w3.org/Bugs/Public/show_bug.cgi?id=15628>). But even if bug 719054 winds up WONTFIX, I still think "px" should be omitted from computed styles:
* The matrix works in all browsers without "px", including Gecko, but only in Gecko with "px".
* A length or percentage is always resolved to "px" anyway, so the length unit never adds anything. It's not like Gecko outputs things like "50%" in the last entries, where you'd lose information by converting to pixels.
* Without "px" it's shorter.
* All other browsers omit "px" already, so if we want interop, the no-"px" behavior is easiest to converge on.
I can see the advantages to *accepting* length units in these entries, but not *outputting* them.
Created attachment 595748 [details] [diff] [review]
David Baron said in bug 719054 comment 1 that <length>/<percentage> should still be accepted in matrix()/matrix3d() until we unprefix. But even if that's the case, I don't see any reason why it should be output in getComputedStyle().
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