Focusable: Fix handling of visibility: inherit

[scottgonzalez]

Ref #14596
Ref gh-1583

[jzaefferer]

Tests?

[jzaefferer]

Nevermind, saw your comment about IE8. Looks good to me.

[scottgonzalez]

I can add a test that explicitly assigned visibility: inherit which would cause all browsers to hit this code path.

[jzaefferer]

That seems useful.

[westonruter]

Should this also check for element.length !== 0 to avoid a possible infinite loop?

[scottgonzalez]

There is no possible infinite loop here. If the element doesn't exist, it can't have a visibility of "inherit".

[westonruter]

Of course. 👍

[scottgonzalez]

Tests added. It turns out that even with these tests, only IE 8 will hit the new code path. All other browsers resolve inherit to either hidden or visible when getting the computed value (which makes sense). As such, I've marked the visible() method as supporting IE 8, but not the tests. The test cases are still valid, and if the implementation were to ever change to checking element.style instead of the computed style, the tests would catch the failure (unless the tree walking logic still existed).

[jzaefferer]

Looks good. Somewhat related: medialize/ally.js#41