Add latest changes from gitlab-org/gitlab@master

jest.config.js

@@ -0,0 +1,17 @@
+const baseConfig = require('./jest.config.base');
+
+module.exports = {
+  ...baseConfig('spec/frontend'),
+};
+
+const karmaTestFile = process.argv.find(arg => arg.includes('spec/javascripts/'));
+if (karmaTestFile) {
+  console.error(`
+Files in spec/javascripts/ and ee/spec/javascripts need to be run with Karma.
+Please use the following command instead:
+
+yarn karma -f ${karmaTestFile}
+
+`);
+  process.exit(1);
+}