Add 2 noop methods to `WP_List_Table`: `->column_default()` and `->column_cb()`.

`WP_List_Table` is essentially an `abstract` class. Some of its methods throw `die()` warnings if they aren't overridden in a child class.

These noop methods wouldn't be `abstract`, because they are not required in subclasses. However, `WP_List_Table` can call these methods in its own method, `->single_row_columns()`, whether a subclass defined them or not.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@31210


git-svn-id: http://core.svn.wordpress.org/trunk@31191 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-list-table.php

@@ -1033,6 +1033,10 @@ class WP_List_Table {
 		echo '</tr>';
 	}
 
+	public function column_default( $item, $column_name ) {}
+
+	public function column_cb( $item ) {}
+	
 	/**
 	 * Generates the columns for a single row of the table
 	 *

wp-includes/version.php

@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.2-alpha-31209';
+$wp_version = '4.2-alpha-31210';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.