fix(v2): allow async/await in live code editor (#3954)

* transforming async functions is not implemented by buble, so just bypassing it would relieve the pain for now

packages/docusaurus-theme-live-codeblock/src/custom-buble.js

@@ -0,0 +1,20 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+// fork of Buble which removes Buble's large dependency and weighs in
+// at a smaller size of ~51kB
+// https://github.com/FormidableLabs/react-live#what-bundle-size-can-i-expect
+const {transform, features: bubleFeatures} = require('@philpl/buble');
+
+// This file is designed to mimic what's written in
+// https://github.com/kitten/buble/blob/mini/src/index.js, with custom transforms options,
+// so that webpack can consume it correctly.
+exports.features = bubleFeatures;
+
+exports.transform = function customTransform(source, options) {
+  return transform(source, {...options, transforms: {asyncAwait: false}});
+};

packages/docusaurus-theme-live-codeblock/src/index.js

@@ -19,10 +19,7 @@ module.exports = function () {
       return {
         resolve: {
           alias: {
-            // fork of Buble which removes Buble's large dependency and weighs in
-            // at a smaller size of ~51kB
-            // https://github.com/FormidableLabs/react-live#what-bundle-size-can-i-expect
-            buble: '@philpl/buble',
+            buble: path.resolve(__dirname, './custom-buble.js'),
           },
         },
       };