Widget Customizer: Fix shift+click issue in Firefox to open a widget.

props westonruter.
see #27358.
Built from https://develop.svn.wordpress.org/trunk@27701


git-svn-id: http://core.svn.wordpress.org/trunk@27540 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/js/customize-widgets.js

@@ -1423,7 +1423,7 @@ var WidgetCustomizer = ( function ($) {
 			var control = this;
 			control.expandControlSection();
 			control.expandForm();
-			control.container.find( ':focusable:first' ).focus().trigger( 'click' );
+			control.container.find( '.widget-content :focusable:first' ).focus();
 		},
 
 		/**