As part of work to add more spec support to the HTML API, this patch adds stubs for all of the remaining parser insertion modes in the HTML Processor. These modes are not all supported yet, but they will be necessary to continue adding support for other tags and markup. Developed in https://github.com/WordPress/wordpress-develop/pull/6973 Discussed in https://core.trac.wordpress.org/ticket/61576 Props dmsnell, jonsurrell. See #61576. Built from https://develop.svn.wordpress.org/trunk@58679 git-svn-id: http://core.svn.wordpress.org/trunk@58081 1a063a9b-81f0-0310-95a4-ce76da25c4cd
