Sync/2may2017 markdown (#7107)

* Easy Markdown: saving post_content_filtered even for autosaves

There is an issue with autosaves as they can't be properly restored as the post_content_filtered is not being populated for them.

If someone attempts to restore an autosave, they would get an empty texteditor, as the content is being read from post_content_filtered.

Populating and storing the post_content_filtered even for autosaves addresses this issue.

/z 50817

Merges r134728-wpcom.

* Markdown Bug Fixes and Updates. Also, Jetpack_Options plan sync.

This should bring four files into sync with Jetpack's versions. Hurrah!

@see https://[private link]

Merges r148841-wpcom.

* Markdown: add docblock to new filter.

@see #7107

modules/markdown/easy-markdown.php

@@ -455,6 +455,8 @@ public function wp_insert_post_data( $post_data, $postarr ) {
 			$post_data['post_content'] = apply_filters( 'content_save_pre', $post_data['post_content'] );
 		} elseif ( 0 === strpos( $post_data['post_name'], $post_data['post_parent'] . '-autosave' ) ) {
 			// autosaves for previews are weird
+			/** This filter is already documented in modules/markdown/easy-markdown.php */
+			$post_data['post_content_filtered'] = apply_filters( 'wpcom_untransformed_content', $post_data['post_content'] );
 			$post_data['post_content'] = $this->transform( $post_data['post_content'], array( 'id' => $post_data['post_parent'] ) );
 			/** This filter is already documented in core/wp-includes/default-filters.php */
 			$post_data['post_content'] = apply_filters( 'content_save_pre', $post_data['post_content'] );