The `gallery` shortcode used to accept a SQL chunk for the value of the `orderby` attribute. The reason? `get_posts()` used to be called in the shortcode handler with a query-string blob of arguments passed to it. To mitigate breakage, `sanitize_sql_orderby()` was created in [7592].

`sanitize_sql_orderby()` expects a comma to be present when multiple `orderby` values were passed. The correct syntax for multiple fields is space-delimited. Since [29027], comma-separated values would never be parsed correctly when passed to `WP_Query->parse_orderby()`.

`sanitize_sql_orderby()` is used nowhere else in core, save for the `playlist` shortcode - I only added it there because I was mimic'ing the `gallery` logic. The function call can be removed from both shortcode handlers.
 
See #6476.
Fixes #23873.


git-svn-id: https://develop.svn.wordpress.org/trunk@30068 602fd350-edb4-49c9-b593-d223f7449a82
Don't cascade autoprefixer output

Autoprefixer changed the default for cascade from false to true. Our css coding standards do not include the cascade for browser prefixes.
Introduced in r30067

see #30141



git-svn-id: https://develop.svn.wordpress.org/trunk@30069 602fd350-edb4-49c9-b593-d223f7449a82
Autoprefix box sizing

Results are from running grunt autoprefix.  Needed for FF before 29 and Safari before 5.1.

fixes #27553



git-svn-id: https://develop.svn.wordpress.org/trunk@30070 602fd350-edb4-49c9-b593-d223f7449a82
Introduce wp_is_trusted_network()

A first step to establish concepts around trusted and untrusted networks.

* Will always return false as default.
* Will one day have a filter.

Fixes #30145


git-svn-id: https://develop.svn.wordpress.org/trunk@30071 602fd350-edb4-49c9-b593-d223f7449a82
Twenty Fifteen: Use a heading heirarchy to provide a better navigation experience when using screenreading software.

Props davidakennedy, rianrietveld, iamtakashi, afercia, davidakennedy, fixes #30065.


git-svn-id: https://develop.svn.wordpress.org/trunk@30072 602fd350-edb4-49c9-b593-d223f7449a82
Adjust caching for `get_term_by()` calls:

* Remove md5 hashes for term name cache keys
* Remove the namespace for the keys for `names` and `slugs` and add them to the group names
* Remove `wp_get_last_changed()`, which @nacin hated
 
Props tollmanz.
Fixes #21760.


git-svn-id: https://develop.svn.wordpress.org/trunk@30073 602fd350-edb4-49c9-b593-d223f7449a82
Introduce a new means of outputting a `<title>` tag in the theme head. Requires a theme to add support by calling `add_theme_support( 'title-tag' )`. This is the first step in adding a more robust means of generating and outputting the title tag.

See #18548.
Props obenland, chrisbliss18, joostdevalk.



git-svn-id: https://develop.svn.wordpress.org/trunk@30074 602fd350-edb4-49c9-b593-d223f7449a82
Define `JSON_PRETTY_PRINT` so it can be used with `wp_json_encode()`

* `JSON_PRETTY_PRINT` was introduced in PHP 5.4
* Now you can use it with lower PHP versions, without a notice

fixes #30139
see #28786

git-svn-id: https://develop.svn.wordpress.org/trunk@30075 602fd350-edb4-49c9-b593-d223f7449a82
In `_wp_handle_upload()`, if `test_upload` is set to `false` in the array of dangerous overrides that the function allows, the only thing that happens when an upload fails is more potential breakage.

`$test_uploaded_file` lets is know if `$file['tmp_name']` exists, which allows to exit with an error, instead of continuing to attempt to move the file.

`$test_upload` override is now a noop.

Fixes #28208.


git-svn-id: https://develop.svn.wordpress.org/trunk@30076 602fd350-edb4-49c9-b593-d223f7449a82
Update inline docs for [30052].

Fixes #23261.

git-svn-id: https://develop.svn.wordpress.org/trunk@30077 602fd350-edb4-49c9-b593-d223f7449a82
Docs and code standards cleanup for [30055] (`wp_json_encode()` & friends)

fixes #28786
props TobiasBg

git-svn-id: https://develop.svn.wordpress.org/trunk@30078 602fd350-edb4-49c9-b593-d223f7449a82
Update images based on grunt imagemin

The new version of imagemin that was added in r30059 condenses some images more.

see #30141



git-svn-id: https://develop.svn.wordpress.org/trunk@30079 602fd350-edb4-49c9-b593-d223f7449a82
Remove call to `wp_get_last_changed()` from unit tests.

This function was removed in [30073].

See #21760.

git-svn-id: https://develop.svn.wordpress.org/trunk@30080 602fd350-edb4-49c9-b593-d223f7449a82