add ability to blacklist internal transformers #94

lib/6to5/transformer.js

@@ -64,8 +64,6 @@ Transformer.prototype.transform = function (file) {
 };
 
 Transformer.prototype.canRun = function (file) {
-  if (this.key[0] === "_") return true;
-
   var opts = file.opts;
 
   var blacklist = opts.blacklist;