Tooltip: Preserve the title after disabling twice

Fixes #9719
Closes jquerygh-1154

Author: mwiencek

tests/unit/tooltip/tooltip_methods.js

@@ -54,7 +54,7 @@ test( "open/close with tracking", function() {
 });
 
 test( "enable/disable", function() {
-	expect( 10 );
+	expect( 11 );
 	$.fx.off = true;
 	var tooltip,
 		element = $( "#tooltipped1" ).tooltip();
@@ -82,6 +82,12 @@ test( "enable/disable", function() {
 	element.tooltip( "enable" );
 	equal( element.attr( "title" ), "anchortitle", "title restored on enable" );
 
+	// #9719 - Title should be preserved after disabling twice
+	element.tooltip( "disable" );
+	element.tooltip( "disable" );
+	element.tooltip( "enable" );
+	equal( element.attr( "title" ), "anchortitle", "title restored on enable after being disabled twice" );
+
 	element.tooltip( "open" );
 	tooltip = $( "#" + element.data( "ui-tooltip-id" ) );
 	ok( tooltip.is( ":visible" ) );

ui/jquery.ui.tooltip.js

@@ -129,7 +129,7 @@ $.widget( "ui.tooltip", {
 			if ( element.is( "[title]" ) ) {
 				element
 					.data( "ui-tooltip-title", element.attr( "title" ) )
-					.attr( "title", "" );
+					.removeAttr( "title" );
 			}
 		});
 	},