clean up file

lib/6to5/file.js

@@ -13,9 +13,9 @@ var t         = require("./types");
 var _         = require("lodash");
 
 function File(opts) {
-  this.dynamicImports   = [];
-  this.dynamicImported  = [];
   this.dynamicImportIds = {};
+  this.dynamicImported  = [];
+  this.dynamicImports   = [];
 
   this.dynamicData      = {};
   this.data             = {};
@@ -62,7 +62,6 @@ File.validOptions = [
   "sourceRoot",
   "moduleRoot",
   "moduleIds",
-  "runtime",
   "comments",
   "reactCompat",
   "keepModuleIdExtensions",