Trigger do_variation_action + '_ajax_data'

To allow extensions which add their own variation bulk actions to pass
data back to WooCommerce core's handler so that only one ajax call
is necessary for updating the data.

Previously, a duplicate ajax call would be required as trigger() does
not capture the callbacks return value.

assets/js/admin/meta-boxes-product-variation.js

@@ -666,6 +666,7 @@ jQuery( function( $ ) {
 					break;
 				default :
 					$( 'select.variation_actions' ).trigger( do_variation_action );
+					data = $( 'select.variation_actions' ).triggerHandler( do_variation_action + '_ajax_data', data );
 					break;
 			}