build: move _testing_init into tools; limit web_test concurrency (#21053)

PR Close #21053

tools/testing/init_browser_spec.ts

@@ -0,0 +1,18 @@
+/**
+ * @license
+ * Copyright Google Inc. 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 {TestBed} from '@angular/core/testing';
+import {BrowserDynamicTestingModule, platformBrowserDynamicTesting} from '@angular/platform-browser-dynamic/testing';
+import {NoopAnimationsModule} from '@angular/platform-browser/animations';
+
+TestBed.initTestEnvironment(
+    [BrowserDynamicTestingModule, NoopAnimationsModule], platformBrowserDynamicTesting());
+
+(window as any).isNode = false;
+(window as any).isBrowser = true;
+(window as any).global = window;