Twenty Fifteen: Removes flashing of background behind fixed position elements when scrolling in mobile and desktop Safari.

Props iamtakashi, fixes #29973 and #29987.


git-svn-id: https://develop.svn.wordpress.org/trunk@29926 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: make sure we don't see borders through transparent linked images.

Props iamtakashi, fixes #29963.



git-svn-id: https://develop.svn.wordpress.org/trunk@29927 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: document the site-branding class in header.php.

Props NikV, fixes #29961.



git-svn-id: https://develop.svn.wordpress.org/trunk@29928 602fd350-edb4-49c9-b593-d223f7449a82
Editor-expand:
- Better calculation for the caret position when auto-scrolling while typing.
- Fix auto-scrolling for non-WebKit browsers when the caret is above the top of the editor.
Fixes #29954

git-svn-id: https://develop.svn.wordpress.org/trunk@29929 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: readable comment details in the dark colour scheme.

Props NikV, fixes #29970.



git-svn-id: https://develop.svn.wordpress.org/trunk@29930 602fd350-edb4-49c9-b593-d223f7449a82
Remove invalid `continue` calls from WP_Tax_Query::get_sql_for_clause().

This was leftover code from the previous implementation, which used a `foreach()`
loop. See [29901].

Props nofearinc.
See #29738, #29718.

git-svn-id: https://develop.svn.wordpress.org/trunk@29931 602fd350-edb4-49c9-b593-d223f7449a82