Move gr-endpoint-slot to typescript

Change-Id: I62943fb4ba246e0b121aa79403c0a07e646b8c99

polygerrit-ui/app/elements/plugins/gr-endpoint-slot/gr-endpoint-slot.js

@@ -1,29 +0,0 @@
-/**
- * @license
- * Copyright (C) 2020 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-import {PolymerElement} from '@polymer/polymer/polymer-element.js';
-
-class GrEndpointSlot extends PolymerElement {
-  static get is() { return 'gr-endpoint-slot'; }
-
-  static get properties() {
-    return {
-      name: String,
-    };
-  }
-}
-
-customElements.define(GrEndpointSlot.is, GrEndpointSlot);

polygerrit-ui/app/elements/plugins/gr-endpoint-slot/gr-endpoint-slot.ts

@@ -0,0 +1,39 @@
+/**
+ * @license
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+import {PolymerElement} from '@polymer/polymer/polymer-element';
+import {customElement, property} from '@polymer/decorators';
+
+/**
+ * `gr-endpoint-slot` is used when need control over where
+ * the registered element should appear inside of the endpoint.
+ */
+@customElement('gr-endpoint-slot')
+export class GrEndpointSlot extends PolymerElement {
+  @property({type: String})
+  name!: string;
+}
+
+/**
+ * Mark name as required as `gr-endpoint-slot` without a name
+ * is meaningless.
+ *
+ * This should help catch errors when you assign an element without
+ * name to GrEndpointSlot type.
+ */
+export interface GrEndpointSlot extends PolymerElement {
+  name: string;
+}