Twenty Twelve: Full width when sidebar is not populated

[obenland]

When there is no sidebar, full width styles currently do not get applied to #content.

[obenland]

21254.diff​ Adds .full-width to style declaration, removes a redundant page template check and adds the case of having no sidebar to the $content_width conditional.

[lancewillett]

Replying to obenland:

21254.diff​ Adds .full-width to style declaration, removes a redundant page template check and adds the case of having no sidebar to the $content_width conditional.

Patch looks good, thanks much. One comment is we *might* want the 'full-width' class on the full-width page also, in case we decide to hook in more styles later.

[lancewillett]

In [21279]:

Twenty Twelve: Update full-width handling with a missing CSS selector, and add case of no sidebar to the content_width calculation. Props obenland, fixes #21254.