Improve closeDropdown handling (#532)

* Move hide-dropdown handling to LinkTo

* Fix action, improve docs

* Update item.hbs

web/app/components/x/dropdown-list/item.ts

@@ -124,29 +124,18 @@ export default class XDropdownListItemComponent extends Component<XDropdownListI
     this._domElement = element;
   }
 
+  /**
+   * The action called on clicked. Runs the parent component's
+   * `onItemClick` action, if it exists, and hides the dropdown.
+   * The "link-to" sub-component runs this on the next run loop
+   * to avoid interfering with Ember's <LinkTo> handling.
+   */
   @action onClick() {
     if (this.args.onItemClick) {
       this.args.onItemClick(this.args.value, this.args.attributes);
     }
 
-    /**
-     * In production, close the dropdown on the next run loop
-     * so that we don't interfere with Ember's <LinkTo> handling.
-     *
-     * This approach causes issues when testing, so we
-     * use `schedule` as an approximation.
-     *
-     * TODO: Improve this.
-     */
-    if (Ember.testing) {
-      schedule("afterRender", () => {
-        this.args.hideContent();
-      });
-    } else {
-      next(() => {
-        this.args.hideContent();
-      });
-    }
+    this.args.hideContent();
   }
 
   /**

web/app/components/x/dropdown-list/link-to.hbs

@@ -2,7 +2,7 @@
   data-test-x-dropdown-list-item-link-to
   {{did-insert @registerElement}}
   {{on "mouseenter" @focusMouseTarget}}
-  {{on "click" @onClick}}
+  {{on "click" this.onClick}}
   role={{@role}}
   aria-selected={{@isAriaSelected}}
   tabindex="-1"

web/app/components/x/dropdown-list/link-to.ts

@@ -1,5 +1,8 @@
 import Component from "@glimmer/component";
 import { XDropdownListInteractiveComponentArgs } from "./_shared";
+import { action } from "@ember/object";
+import Ember from "ember";
+import { next, schedule } from "@ember/runloop";
 
 interface XDropdownListLinkToComponentSignature {
   Element: HTMLAnchorElement;
@@ -14,7 +17,23 @@ interface XDropdownListLinkToComponentSignature {
   };
 }
 
-export default class XDropdownListLinkToComponent extends Component<XDropdownListLinkToComponentSignature> {}
+export default class XDropdownListLinkToComponent extends Component<XDropdownListLinkToComponentSignature> {
+  /**
+   * The action to run when the item is clicked.
+   * We wait until the next run loop so that we don't interfere with
+   * Ember's <LinkTo> handling. Because this approach causes issues
+   * when testing, we use `schedule` as an approximation.
+   */
+  @action protected onClick(): void {
+    if (Ember.testing) {
+      schedule("afterRender", this.args.onClick);
+    } else {
+      next(() => {
+        this.args.onClick();
+      });
+    }
+  }
+}
 
 declare module "@glint/environment-ember-loose/registry" {
   export default interface Registry {