Revert change to focusing behaviour in 4.0.6 (#5576)

This behaviour, where the focus was happening on a small asynchronous
delay, was added in commit 933189b92 late last year in a commit with
no supporting tickets or commit message explaining what the change
was trying to accomplish. This commit has effectly been reverted within
this commit, since it caused a regression in how focus was being
assigned that made it inconsistent with a standard `<select>`.

A test was added for this which ensures that we won't see that
regression again.

Fixes #5532
Fixes #5185
Closes #5552

src/js/select2/selection/base.js

@@ -81,9 +81,7 @@ define([
       self.$selection.removeAttr('aria-activedescendant');
       self.$selection.removeAttr('aria-owns');
 
-      window.setTimeout(function () {
+      self.$selection.trigger('focus');
-        self.$selection.trigger('focus');
-      }, 0);
 
       self._detachCloseHandler(container);
     });

tests/selection/focusing-tests.js

@@ -0,0 +1,41 @@
+module('Selection containers - Managing focus');
+
+var SingleSelection = require('select2/selection/single');
+
+var $ = require('jquery');
+var Options = require('select2/options');
+
+var options = new Options({});
+
+test('close sets the focus to the selection', function (assert) {
+  var $container = $('#qunit-fixture .event-container');
+  var container = new MockContainer();
+  var selection = new SingleSelection(
+    $('#qunit-fixture .single'),
+    options
+  );
+
+  var $selection = selection.render();
+  selection.bind(container, $container);
+
+  selection.update([{
+    id: 'test',
+    text: 'test'
+  }]);
+
+  $container.append($selection);
+
+  assert.notEqual(
+    document.activeElement,
+    $selection[0],
+    'The selection had focus originally'
+  );
+
+  container.trigger('close');
+
+  assert.equal(
+    document.activeElement,
+    $selection[0],
+    'After close, focus must be set to selection'
+  );
+});

tests/unit-jq1.html

@@ -87,6 +87,7 @@
 
     <script src="selection/allowClear-tests.js" type="text/javascript"></script>
     <script src="selection/containerCss-tests.js" type="text/javascript"></script>
+    <script src="selection/focusing-tests.js" type="text/javascript"></script>
     <script src="selection/multiple-tests.js" type="text/javascript"></script>
     <script src="selection/placeholder-tests.js" type="text/javascript"></script>
     <script src="selection/search-tests.js" type="text/javascript"></script>

tests/unit-jq2.html

@@ -87,6 +87,7 @@
 
     <script src="selection/allowClear-tests.js" type="text/javascript"></script>
     <script src="selection/containerCss-tests.js" type="text/javascript"></script>
+    <script src="selection/focusing-tests.js" type="text/javascript"></script>
     <script src="selection/multiple-tests.js" type="text/javascript"></script>
     <script src="selection/placeholder-tests.js" type="text/javascript"></script>
     <script src="selection/search-tests.js" type="text/javascript"></script>

tests/unit-jq3.html

@@ -87,6 +87,7 @@
 
     <script src="selection/allowClear-tests.js" type="text/javascript"></script>
     <script src="selection/containerCss-tests.js" type="text/javascript"></script>
+    <script src="selection/focusing-tests.js" type="text/javascript"></script>
     <script src="selection/multiple-tests.js" type="text/javascript"></script>
     <script src="selection/placeholder-tests.js" type="text/javascript"></script>
     <script src="selection/search-tests.js" type="text/javascript"></script>