Add .babelrc.js for a temporary time period

debian/patches/0720-use-babelrc.js-tmp.patch

@@ -0,0 +1,58 @@
+Description: Using .babelrc.js out of babel.config.js for a temporary
+             period of time :)
+Author: Utkarsh Gupta <guptautkarsh2102@gmail.com>
+
+--- /dev/null
++++ gitlab-11.10.4+dfsg/.babelrc.js
+@@ -0,0 +1,51 @@
++/* eslint-disable import/no-commonjs, filenames/match-regex */
++
++const BABEL_ENV = process.env.BABEL_ENV || process.env.NODE_ENV || null;
++
++const presets = [
++  [
++    '@babel/preset-env',
++    {
++      modules: false,
++      targets: {
++        ie: '11',
++      },
++    },
++  ],
++];
++
++// include stage 3 proposals
++const plugins = [
++  '@babel/plugin-syntax-dynamic-import',
++  '@babel/plugin-syntax-import-meta',
++  '@babel/plugin-proposal-class-properties',
++  '@babel/plugin-proposal-json-strings',
++  '@babel/plugin-proposal-private-methods',
++];
++
++// add code coverage tooling if necessary
++if (BABEL_ENV === 'coverage') {
++  plugins.push([
++    'babel-plugin-istanbul',
++    {
++      exclude: ['spec/javascripts/**/*', 'app/assets/javascripts/locale/**/app.js'],
++    },
++  ]);
++}
++
++// add rewire support when running tests
++if (BABEL_ENV === 'karma' || BABEL_ENV === 'coverage') {
++  plugins.push('babel-plugin-rewire');
++}
++
++// Jest is running in node environment
++if (BABEL_ENV === 'jest') {
++  plugins.push('@babel/plugin-transform-modules-commonjs');
++  /*
++  without the following, babel-plugin-istanbul throws an error:
++  https://gitlab.com/gitlab-org/gitlab-ce/issues/58390
++  */
++  plugins.push('babel-plugin-dynamic-import-node');
++}
++
++module.exports = { presets, plugins };

debian/patches/series

@@ -31,3 +31,4 @@
 0690-debian-usage-ping.patch
 0700-add-salsa-link-to-help.patch
 0710-use-yarnpkg.patch
+0720-use-babelrc.js-tmp.patch