Dialog: Fix shift-tab handling, focus the correct element

Copy-paste error introduced in df6110c

Updates the tabbing test to be more specific about which element should
have focus, instead of only checking if focus is within the dialog.

Ref #9646
Ref #10103
Closes gh-1264

tests/unit/dialog/dialog_core.js

@@ -140,28 +140,30 @@ test( "#7960: resizable handles below modal overlays", function() {
asyncTest( "Prevent tabbing out of dialogs", function() {
	expect( 3 );

	var element = $( "<div><input><input></div>" ).dialog(),
		inputs = element.find( "input" ),
		widget = element.dialog( "widget" )[ 0 ];
	var element = $( "<div><input name='0'><input name='1'></div>" ).dialog(),
		inputs = element.find( "input" );

	// Remove close button to test focus on just the two buttons
	element.dialog( "widget" ).find( ".ui-button").remove();

	function checkTab() {
		ok( $.contains( widget, document.activeElement ), "Tab key event moved focus within the modal" );
		equal( document.activeElement, inputs[ 0 ], "Tab key event moved focus within the modal" );

		// check shift tab
		$( document.activeElement ).simulate( "keydown", { keyCode: $.ui.keyCode.TAB, shiftKey: true });
		setTimeout( checkShiftTab );
	}

	function checkShiftTab() {
		ok( $.contains( widget, document.activeElement ), "Shift-Tab key event moved focus within the modal" );
		equal( document.activeElement, inputs[ 1 ], "Shift-Tab key event moved focus back to second input" );

		element.remove();
		setTimeout( start );
	}

	inputs[1].focus();
	inputs[ 1 ].focus();
	setTimeout(function() {
		equal( document.activeElement, inputs[1], "Focus set on second input" );
		equal( document.activeElement, inputs[ 1 ], "Focus set on second input" );
		inputs.eq( 1 ).simulate( "keydown", { keyCode: $.ui.keyCode.TAB });

		setTimeout( checkTab );

ui/dialog.js

@@ -348,7 +348,7 @@ return $.widget( "ui.dialog", {
					event.preventDefault();
				} else if ( ( event.target === first[0] || event.target === this.uiDialog[0] ) && event.shiftKey ) {
					this._delay(function() {
						first.focus();
						last.focus();
					});
					event.preventDefault();
				}