[patch][cla][enhancement] Claro: support cross-browser CSS3 Transitions

[Kenneth G. Franqueiro]

Claro currently only contains webkit vendor-specific transition styles.

I'm attaching a patch that adds -moz and standard properties as well, using LESS mixins like I did for box-shadow and border-radius previously.

Unfortunately, it seems to me there's no way to define a mixin with unknown number of parameters (I'd love to be wrong here), but apparently "overloading" mixins with differing numbers of input parameters works, so I include one- and two-parameter versions of the transition-property and transition-duration mixins, since claro currently specifies two values in some places.

This is admittedly unscalable, since we'd have to add more mixins if we ever specify more than two values, but IMO it's still more scalable than having the several vendor-specific and standard properties specified all across the theme files.

We could easily add opera-specific properties to these mixins; I abstained for the time being, partly because I observed glitches when I tried it (for instance, Opera seems to think the light-blue-to-lighter-blue transition on the month menu in the calendar should involve light red in the process).

Of course, this is all somewhat up in the air - do others think this is worth the extra bytes introduced? (Not sure if any browsers pick up the non-vendor-specific properties yet, maybe -webkit and -moz are enough for now?)

[Kenneth G. Franqueiro]

Changes to .less files for cross-browser CSS transitions

[Kenneth G. Franqueiro]

Changes to .css files for cross-browser CSS transitions

[bill]

Sure, looks good to me, I'm OK with this in 1.7 or 1.6.1. (Could theoretically target for 1.6.1 as a FF4/IE9 fix.)

[Kenneth G. Franqueiro]

For some reason it looks like trac didn't pick up my commit to trunk; see [24192].

Going to potentially ask a few more people for opinions before shoving it in 1.6.1 (I think it'd be nice to).

[Adam Peller]

I agree with Bill. I don't think of this so much as a feature enhancement as a bug fix anyway.

[Kenneth G. Franqueiro]

(In [24196]) Fixes #12581 on 1.6 branch: apply same changes as [24192] for cross-browser CSS transitions in Claro. Also fix a previously-unsynchronized line from Tree.less in Tree.css.