wp_add_inline_style():
* Change the `wp-inline-style-$handle` class added in [29956] to `$handle-inline-css` for consistency with existing patterns.
* Add the ID attribute when concatenation is enabled as well.

props georgestephanis.
see #30032.

git-svn-id: https://develop.svn.wordpress.org/trunk@29958 602fd350-edb4-49c9-b593-d223f7449a82