Don't include in browser build

This addresses an OOM in Saucelabs, since  tries to make grpc-js work in IE11. We should not include any tests that depend on GRPC-JS

Author: schmidt-sebastian

packages/firestore/test/unit/bootstrap.ts

@@ -29,5 +29,5 @@ import '../../src/platform_browser/browser_init';
 const testsContext = (require as any).context('.', true, /.test$/);
 const browserTests = testsContext
   .keys()
-  .filter((file: string) => file.indexOf('/node/') < 0);
+  .filter((file: string) => !file.match(/([\/.])node([\/.])/));
 browserTests.forEach(testsContext);

packages/firestore/test/unit/remote/serializer.browser.test.ts

@@ -0,0 +1,3 @@
+import {serializerTest} from "./serializer.helper";
+
+serializerTest();