Dialog: Stop tracking instance in destroy() to avoid memory leaks

Fixes #11125

Author: tjvantoll

ui/dialog.js

@@ -155,6 +155,7 @@ return $.widget( "ui.dialog", {
 		var next,
 			originalPosition = this.originalPosition;
 
+		this._stopTrackingInstance();
 		this._destroyOverlay();
 
 		this.element
@@ -623,6 +624,17 @@ return $.widget( "ui.dialog", {
 		return instances;
 	},
 
+	_stopTrackingInstance: function() {
+		var i = 0,
+			instances = this._trackingInstances();
+
+		for ( ; i < instances.length; i++ ) {
+			if ( instances[ i ] === this ) {
+				instances.splice( i, 1 );
+			}
+		}
+	},
+
 	_minHeight: function() {
 		var options = this.options;