Widget: Avoid memory leaks when unbinding events with ._off()

Ref #10056
Ref jquerygh-1319

Author: scottgonzalez

ui/widget.js

@@ -442,8 +442,14 @@ $.Widget.prototype = {
 	},
 
 	_off: function( element, eventName ) {
-		eventName = (eventName || "").split( " " ).join( this.eventNamespace + " " ) + this.eventNamespace;
+		eventName = (eventName || "").split( " " ).join( this.eventNamespace + " " ) +
+			this.eventNamespace;
 		element.unbind( eventName ).undelegate( eventName );
+
+		// Clear the stack to avoid memory leaks (#10056)
+		this.bindings = $( this.bindings.not( element ).get() );
+		this.focusable = $( this.focusable.not( element ).get() );
+		this.hoverable = $( this.hoverable.not( element ).get() );
 	},
 
 	_delay: function( handler, delay ) {