Twenty Twelve: Add Google font support to custom header admin

[obenland]

Related: #22499

We should also add Open Sans to the custom header admin, to correctly display the site title and description.

[lancewillett]

Quick notes, also '444' mention in a PHP comment (near line 66) -- and probably should use font_url singular as the variable name (to match the functions.php change, and since it's only one font).

[lancewillett]

In 23717:

Twenty Twelve: improve Appearance > Header styles to match front end view better -- including loading special Google Font there. Props obenland, fixes #23790.

[SergeyBiryukov]

In [23717], there are 3 instances of ​zero width space before the font names.

23790.2.diff​ fixes that.

[lancewillett]

Replying to SergeyBiryukov:

In [23717], there are 3 instances of ​zero width space before the font names.

Good catch! How did you find that?

[lancewillett]

In 24013:

Twenty Twelve: remove zero-width spaces in CSS value, props SergeyBiryukov. Closes #23790.

[lancewillett]

In 24014:

Twenty Twelve: add back missing space in CSS value, removed in r24013. See #23790.

[SergeyBiryukov]

Replying to lancewillett:

Good catch! How did you find that?

Noticed in the editors I use (Far Manager and Notepad++) while preparing a patch for #24033.

[lancewillett]

Replying to SergeyBiryukov:

Replying to lancewillett:

Good catch! How did you find that?

Noticed in the editors I use (Far Manager and Notepad++) while preparing a patch for #24033.

Do you have a setting turned on for "show invisible characters" or something like that?

[SergeyBiryukov]

Replying to lancewillett:

Do you have a setting turned on for "show invisible characters" or something like that?

Just for whitespace and tabs. Zero-width spaces showed up as empty squares: 23790.zero-width-space.png​.