drop helpers/clone

it's misleading as it doesn't actually do a deepClone, not even a clone

lib/babel/helpers/clone.js

@@ -1,12 +0,0 @@
-"use strict";
-
-module.exports = function cloneDeep(obj) {
-  var obj2 = {};
-  if (!obj) return obj2;
-
-  for (var key in obj) {
-    obj2[key] = obj[key];
-  }
-
-  return obj2;
-};

lib/babel/transformation/file.js

@@ -10,7 +10,7 @@ var transform          = require("./index");
 var generate           = require("../generation");
 var defaults           = require("lodash/object/defaults");
 var includes           = require("lodash/collection/includes");
-var clone              = require("../helpers/clone");
+var assign             = require("lodash/object/assign");
 var parse              = require("../helpers/parse");
 var Scope              = require("../traversal/scope");
 var slash              = require("slash");
@@ -98,7 +98,7 @@ File.validOptions = [
 ];
 
 File.prototype.normalizeOptions = function (opts) {
-  opts = clone(opts);
+  opts = assign({}, opts);
 
   for (var key in opts) {
     if (key[0] !== "_" && File.validOptions.indexOf(key) < 0) {

lib/babel/transformation/transformer.js

@@ -6,7 +6,7 @@ var TransformerPass = require("./transformer-pass");
 var isFunction      = require("lodash/lang/isFunction");
 var traverse        = require("../traversal");
 var isObject        = require("lodash/lang/isObject");
-var clone           = require("../helpers/clone");
+var assign          = require("lodash/object/assign");
 var each            = require("lodash/collection/each");
 
 /**
@@ -16,7 +16,7 @@ var each            = require("lodash/collection/each");
  */
 
 function Transformer(key, transformer, opts) {
-  transformer = clone(transformer);
+  transformer = assign({}, transformer);
 
   var take = function (key) {
     var val = transformer[key];