[ts] Type-check ui/ListModel.js with TypeScript

R=aerotwist@chromium.org

Bug: chromium:1011811
Change-Id: I806598d864d40eab506b1e02483fad8168aba3f2
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2352728
Reviewed-by: Paul Lewis <aerotwist@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>

front_end/ui/ListModel.js

@@ -2,9 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// @ts-nocheck
-// TODO(crbug.com/1011811): Enable TypeScript compiler checks
-
 import * as Common from '../common/common.js';
 
 /**
@@ -17,6 +14,7 @@ export class ListModel extends Common.ObjectWrapper.ObjectWrapper {
    */
   constructor(items) {
     super();
+    /** @type {!Array<T>} */
     this._items = items || [];
   }
 
@@ -146,7 +144,7 @@ export class ListModel extends Common.ObjectWrapper.ObjectWrapper {
       // Splice may fail with too many arguments.
       const before = this._items.slice(0, from);
       const after = this._items.slice(to);
-      this._items = [].concat(before, items, after);
+      this._items = [...before, ...items, ...after];
     }
     this._replaced(from, removed, items.length);
     return removed;