Allow for easier adding of custom class variables when extending WP_Customize_Section or WP_Customize_Setting.

props rhurling.
fixes #27315.
Built from https://develop.svn.wordpress.org/trunk@28827


git-svn-id: http://core.svn.wordpress.org/trunk@28631 1a063a9b-81f0-0310-95a4-ce76da25c4cd
wpLink: support whole URLs including query/fragment when pre-filling the URL field. Fixes #19992
Built from https://develop.svn.wordpress.org/trunk@28828


git-svn-id: http://core.svn.wordpress.org/trunk@28632 1a063a9b-81f0-0310-95a4-ce76da25c4cd