add data abstraction layer to File

lib/6to5/file.js

@@ -14,6 +14,7 @@ var _         = require("lodash");
 function File(opts) {
   this.dynamicImports   = [];
   this.dynamicImportIds = {};
+  this.data             = {};
   this.opts             = File.normaliseOptions(opts);
   this.transformers     = this.getTransformers();
   this.uids             = {};
@@ -175,6 +176,14 @@ File.prototype.parseShebang = function (code) {
   return code;
 };
 
+File.prototype.set = function (key, val) {
+  this.data[key] = val;
+};
+
+File.prototype.get = function (key) {
+  return this.data[key];
+};
+
 File.prototype.addImport = function (source, name) {
   name = name || source;
   var id = this.dynamicImportIds[name];
@@ -201,20 +210,19 @@ File.prototype.addHelper = function (name) {
   var declar = program._declarations && program._declarations[name];
   if (declar) return declar.id;
 
-  var ref;
-  if (this._runtime) {
-    return t.memberExpression(this._runtime, name);
+  var runtime = this.get("runtimeIdentifier");
+  if (runtime) {
+    return t.memberExpression(runtime, name);
   } else {
-    ref = util.template(name);
+    var ref = util.template(name);
+    var uid = this.generateUidIdentifier(name);
+    this.scope.push({
+      key: name,
+      id: uid,
+      init: ref
+    });
+    return uid;
   }
-
-  var uid = this.generateUidIdentifier(name);
-  this.scope.push({
-    key: name,
-    id: uid,
-    init: ref
-  });
-  return uid;
 };
 
 File.prototype.errorWithNode = function (node, msg, Error) {