Twenty Ten 1.2 compat for WP 3.0

[nacin]

The theme directory doesn't have compatibility checks. Additionally, Twenty Ten was 3.0's default theme, so it should remain compat.

Issues:

1. get_post_format() function_exists() checks, handled in r17474 and r17469.

2. use_default_gallery_style filter doesn't exist in 3.0.

3. show_recent_comments_widget_style filter doesn't exist in 3.0.

Neither of these are important. I honestly don't care much if we lose compatibility on those layers. But working on patches.

Looks like we'll need to do a raw version compare for these. did_action() would work for use_default_gallery_style filter, except that it doesn't work for filters. show_recent_comments_widget_style would be pretty tough to detect otherwise.

Untested and unconvinced.

Second patch handles gallery style and ignores recent comments style.

Looks good.

(In [17477]) Back compat with the gallery_style filter in Twenty Ten. fixes #16610 for the 3.1 branch.

(In [17478]) Back compat with the gallery_style filter in Twenty Ten. fixes #16610 for trunk.