add includeRegenerator option

bin/6to5/index.js

@@ -25,6 +25,7 @@ commander.option("-I, --indent [width]", "Indent width [2]", 2);
 commander.option("-a, --amd-module-ids", "Insert module id in AMD modules", false); // todo: remove in 3.0.0
 commander.option("-m, --module-ids", "Insert module id in modules", false);
 commander.option("-R, --react-compat", "Makes the react transformer produce pre-v0.12 code");
+commander.option("-E, --include-regenerator", "Include the regenerator runtime if necessary", false);
 
 commander.on("--help", function(){
   var outKeys = function (title, obj) {
@@ -100,18 +101,19 @@ if (errors.length) {
 //
 
 exports.opts = {
-  sourceMapName: commander.outFile,
-  experimental:  commander.experimental,
-  playground:    commander.playground,
-  moduleIds:     commander.amdModuleIds || commander.moduleIds,
-  blacklist:     commander.blacklist,
-  whitelist:     commander.whitelist,
-  sourceMap:     commander.sourceMaps || commander.sourceMapsInline,
-  optional:      commander.optional,
-  comments:      !commander.removeComments,
-  runtime:       commander.runtime,
-  modules:       commander.modules,
-  reactCompat:   commander.reactCompat,
+  includeRegenerator: commander.includeRegenerator,
+  sourceMapName:      commander.outFile,
+  experimental:       commander.experimental,
+  reactCompat:        commander.reactCompat,
+  playground:         commander.playground,
+  moduleIds:          commander.amdModuleIds || commander.moduleIds,
+  blacklist:          commander.blacklist,
+  whitelist:          commander.whitelist,
+  sourceMap:          commander.sourceMaps || commander.sourceMapsInline,
+  optional:           commander.optional,
+  comments:           !commander.removeComments,
+  runtime:            commander.runtime,
+  modules:            commander.modules,
   format: {
     indent: {
       style:     util.repeat(parseInt(commander.indent))

lib/6to5/file.js

@@ -48,21 +48,22 @@ File.normaliseOptions = function (opts) {
   opts = _.cloneDeep(opts || {});
 
   _.defaults(opts, {
-    experimental: false,
-    reactCompat:  false,
-    playground:   false,
-    whitespace:   true,
-    moduleIds:    opts.amdModuleIds || false,
-    blacklist:    [],
-    whitelist:    [],
-    sourceMap:    false,
-    optional:     [],
-    comments:     true,
-    filename:     "unknown",
-    modules:      "common",
-    runtime:      false,
-    code:         true,
-    ast:          true
+    includeRegenerator: false,
+    experimental:       false,
+    reactCompat:        false,
+    playground:         false,
+    whitespace:         true,
+    moduleIds:          opts.amdModuleIds || false,
+    blacklist:          [],
+    whitelist:          [],
+    sourceMap:          false,
+    optional:           [],
+    comments:           true,
+    filename:           "unknown",
+    modules:            "common",
+    runtime:            false,
+    code:               true,
+    ast:                true
   });
 
   // normalise windows path separators to unix

lib/6to5/transformation/transformers/es6-generators.js

@@ -1,3 +1,9 @@
+var regenerator = require("regenerator");
+
 exports.ast = {
-  before: require("regenerator").transform
+  before: function (ast, file) {
+    regenerator.transform(ast, {
+      includeRuntime: file.opts.includeRegenerator && "if used"
+    });
+  }
 };