Return full result from babel.transform.

Previous code only returns an object of the shape `{ code, map, metadata }` which prevents accessing things like the AST when `babel` is configured to output it. This change allows access to whatever `babel` spits back out.

src/transform.js

@@ -14,13 +14,13 @@ module.exports = async function(source, options) {
 
   if (!result) return null;
 
-  const { code, map, metadata } = result;
+  const { map } = result;
 
   if (map && (!map.sourcesContent || !map.sourcesContent.length)) {
     map.sourcesContent = [source];
   }
 
-  return { code, map, metadata };
+  return result;
 };
 
 module.exports.version = babel.version;