add modules common strict formatter - fixes #418

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

@@ -0,0 +1,11 @@
+module.exports = CommonJSStrictFormatter;
+
+var CommonJSFormatter = require("./common");
+var util              = require("../../util");
+
+function CommonJSStrictFormatter() {
+  this.noInteropExport = true;
+  CommonJSFormatter.apply(this, arguments);
+}
+
+util.inherits(CommonJSStrictFormatter, CommonJSFormatter);

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

@@ -61,7 +61,7 @@ CommonJSFormatter.prototype.importDeclaration = function (node, nodes) {
 };
 
 CommonJSFormatter.prototype.exportDeclaration = function (node, nodes) {
-  if (node.default && !this.exportIdentifier) {
+  if (node.default && !this.noInteropRequire && !this.noInteropExport) {
     var declar = node.declaration;
     var assign;
 

lib/6to5/transformation/transform.js

@@ -31,11 +31,12 @@ transform._ensureTransformerNames = function (type, keys) {
 transform.transformers = {};
 
 transform.moduleFormatters = {
-  common: require("./modules/common"),
-  system: require("./modules/system"),
-  ignore: require("./modules/ignore"),
-  amd:    require("./modules/amd"),
-  umd:    require("./modules/umd")
+  commonStrict: require("./modules/common-strict"),
+  common:       require("./modules/common"),
+  system:       require("./modules/system"),
+  ignore:       require("./modules/ignore"),
+  amd:          require("./modules/amd"),
+  umd:          require("./modules/umd")
 };
 
 _.each({