Upgrade webpack to v2 and other deps (#8491)

* update to webpack2 and other deps

* fix linting

webpack/webpack.test.conf.js

@@ -0,0 +1,24 @@
+// This is the webpack config used for unit tests.
+const merge = require('webpack-merge');
+const baseConfig = require('./webpack.base.conf');
+const utils = require('./utils');
+const webpack = require('webpack');
+const testEnv = require('./config/test.env');
+
+const webpackConfig = merge(baseConfig, {
+  // use inline sourcemap for karma-sourcemap-loader
+  module: {
+    rules: utils.styleLoaders(),
+  },
+  devtool: '#inline-source-map',
+  plugins: [
+    new webpack.DefinePlugin({
+      'process.env': testEnv,
+    }),
+  ],
+});
+
+// no need for app entry during tests
+delete webpackConfig.entry;
+
+module.exports = webpackConfig;