Don't open a pointer when the target element is hidden. see #19357.

git-svn-id: https://develop.svn.wordpress.org/trunk@19467 602fd350-edb4-49c9-b593-d223f7449a82

wp-includes/js/wp-pointer.dev.js

@@ -220,6 +220,9 @@
 			if ( this.active || o.disabled )
 				return;
 
+			if ( this.element.is(':hidden') )
+				return;
+
 			this.update().done( function() {
 				self._open( event );
 			});