Improve some docs for @param. Remove an unneeded $wpdb global import.

See #30799.

Built from https://develop.svn.wordpress.org/trunk@30979


git-svn-id: http://core.svn.wordpress.org/trunk@30965 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-image-editor-imagick.php

@@ -190,6 +190,8 @@ class WP_Image_Editor_Imagick extends WP_Image_Editor {
 	 *
 	 * @param int $width
 	 * @param int $height
+	 *
+	 * @return true|WP_Error
 	 */
 	protected function update_size( $width = null, $height = null ) {
 		$size = null;