Blocks: Add the reusable block post type, wp_block.

Merges [43804] from the 5.0 branch to trunk.

See #45098.

Built from https://develop.svn.wordpress.org/trunk@44146


git-svn-id: http://core.svn.wordpress.org/trunk@43976 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/capabilities.php

@@ -574,6 +574,23 @@ function map_meta_cap( $cap, $user_id ) {
 				return call_user_func_array( 'map_meta_cap', $args );
 			}
 
+			// Block capabilities map to their post equivalent.
+			$block_caps = array(
+				'edit_blocks',
+				'edit_others_blocks',
+				'publish_blocks',
+				'read_private_blocks',
+				'delete_blocks',
+				'delete_private_blocks',
+				'delete_published_blocks',
+				'delete_others_blocks',
+				'edit_private_blocks',
+				'edit_published_blocks',
+			);
+			if ( in_array( $cap, $block_caps, true ) ) {
+				$cap = str_replace( '_blocks', '_posts', $cap );
+			}
+
 			// If no meta caps match, return the original cap.
 			$caps[] = $cap;
 	}