Experiment: cast objects to string (eliminates one Map/object differe…

…nce per https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map )

packages/babel-plugin-transform-block-scoping/src/index.js

@@ -340,7 +340,7 @@ const loopVisitor = {
 
 function extendMap(map, obj) {
   for (const key of Object.keys(obj)) {
-    map.set(key, obj[key]);
+    map.set(key, String(obj[key]));
   }
 }