Updated the files.

my-app/node_modules/@angular-devkit/schematics/tasks/package-manager/install-task.d.ts

@@ -0,0 +1,29 @@
+/**
+ * @license
+ * Copyright Google LLC All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+import { TaskConfiguration, TaskConfigurationGenerator } from '../../src';
+import { NodePackageTaskOptions } from './options';
+interface NodePackageInstallTaskOptions {
+    packageManager?: string;
+    packageName?: string;
+    workingDirectory?: string;
+    quiet?: boolean;
+    hideOutput?: boolean;
+    allowScripts?: boolean;
+}
+export declare class NodePackageInstallTask implements TaskConfigurationGenerator<NodePackageTaskOptions> {
+    quiet: boolean;
+    hideOutput: boolean;
+    allowScripts: boolean;
+    workingDirectory?: string;
+    packageManager?: string;
+    packageName?: string;
+    constructor(workingDirectory?: string);
+    constructor(options: NodePackageInstallTaskOptions);
+    toConfiguration(): TaskConfiguration<NodePackageTaskOptions>;
+}
+export {};