[Patch] transfile proxy polyfill (#112)

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| Q                | A
| ---------------- | ---
| Bug fix?         | yes
| New feature?     | no
| Breaking change? | no
| Deprecations?    | no
| Documentation?   | no
| Tests added?     | no

<!-- Describe your changes below in detail. -->

Fixes an issue in which Proxy Polyfill didn't get transpiled and added as es6 to the bundle.

babel.config.js

@@ -0,0 +1,22 @@
+module.exports = (api) => {
+    api.cache(true);
+
+    const presets = [
+        '@babel/preset-flow',
+        '@babel/preset-env'
+    ];
+
+    const plugins = [
+        '@babel/plugin-transform-flow-strip-types',
+        ['webpack-aliases', {
+            'config': 'webpack.config.js'
+        }],
+        'babel-plugin-add-module-exports',
+        '@babel/plugin-proposal-class-properties'
+    ];
+
+    return {
+        presets,
+        plugins
+    };
+};