build: cronjob cannot install angular snapshot builds

Apparently the script that also ran on `TravisCI` does not work on MacOS, nor on CircleCI because it's not
guaranteed that the default `awk` supports storing `match()` results in an array that can print individual
match groups.

Author: devversion

.circleci/config.yml

@@ -279,7 +279,7 @@ jobs:
     - *restore_cache
     - *yarn_install
 
-    - run: ./scripts/install-angular-snapshots.sh
+    - run: node ./scripts/install-angular-snapshots.js
     - run: ./scripts/circleci/run-local-browser-tests.sh
 
 # ----------------------------------------------------------------------------------------
@@ -303,6 +303,8 @@ workflows:
       - tests_local_browsers
       - tests_browserstack
       - tests_saucelabs
+      # Testing
+      - snapshot_tests_local_browsers
 
   integration_tests:
     jobs:

scripts/install-angular-snapshots.js

@@ -0,0 +1,28 @@
+/*
+ * Script that re-installs all Angular dependencies using the GitHub build snapshots. We need to
+ * do this after the locked node modules have been installed because otherwise `--frozen-lockfile`
+ * would complain about outdated lock files.
+ */
+
+const join = require('path').join;
+const execSync = require('child_process').execSync;
+const packageJson = require('../package.json');
+
+// List of Angular packages that are specified in the "package.json". Packages will be listed
+// without the "@angular/" scope.
+const angularPackages = Object
+  .keys({...packageJson.dependencies, ...packageJson.devDependencies})
+  .filter(depName => depName.startsWith('@angular/'))
+  .map(depName => depName.split('/').slice(1));
+
+// List of URLs that refer to the Github snapshot builds for all Angular packages.
+const githubBuildUrls = angularPackages.map(name => `github:angular/${name}-builds`);
+
+// Run yarn add {URLs}, so that it replaces the Angular npm packages with the Github builds.
+execSync(`yarn add ${githubBuildUrls.join(' ')}`, {
+  stdio: 'inherit',
+  shell: true,
+  cwd: join(__dirname, '../')
+});
+
+console.log('Finished installing the Angular snapshot builds.');