add back strict module formatters

lib/6to5/transformation/modules/_strict.js

@@ -0,0 +1,14 @@
+"use strict";
+
+var util = require("../../util");
+
+module.exports = function (Parent) {
+  var Constructor = function () {
+    this.noInteropRequire = true;
+    Parent.apply(this, arguments);
+  };
+
+  util.inherits(Constructor, Parent);
+
+  return Constructor;
+};

lib/6to5/transformation/modules/amd-strict.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./amd"));

lib/6to5/transformation/modules/amd.js

@@ -99,7 +99,7 @@ AMDFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
 };
 
 AMDFormatter.prototype.exportDeclaration = function (node) {
-  if (node.default && !this.noInteropRequire && !this.hasNonDefaultExports) {
+  if (this.doDefaultExportInterop(node)) {
     this.passModuleArg = true;
   }
 

lib/6to5/transformation/modules/common-strict.js

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./common"));

lib/6to5/transformation/modules/common.js

@@ -60,8 +60,12 @@ CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
   }, true));
 };
 
+CommonJSFormatter.prototype.doDefaultExportInterop = function (node) {
+  return node.default && !this.noInteropRequire && !this.hasNonDefaultExports;
+};
+
 CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
-  if (node.default && !this.noInteropRequire && !this.hasNonDefaultExports) {
+  if (this.doDefaultExportInterop(node)) {
     var declar = node.declaration;
     var assign = util.template("exports-default-assign", {
       VALUE: this._pushStatement(declar, nodes)

lib/6to5/transformation/modules/umd-strict

@@ -0,0 +1,3 @@
+"use strict";
+
+module.exports = require("./_strict")(require("./umd"));

lib/6to5/transformation/transform.js

@@ -86,6 +86,9 @@ transform.deprecatedTransformerMap = {
 transform.transformers = object();
 
 transform.moduleFormatters = {
+  commonStrict: require("./modules/common-strict"),
+  amdStrict:    require("./modules/amd-strict"),
+  umdStrict:    require("./modules/umd-strict"),
   common:       require("./modules/common"),
   system:       require("./modules/system"),
   ignore:       require("./modules/ignore"),