packager: enable @flow in bundle/buildBundle.js

Reviewed By: cpojer

Differential Revision: D4377362

fbshipit-source-id: decd5ff9b245c9dfd4bb9af6e41717ee860fc1ba

local-cli/bundle/buildBundle.js

@@ -5,7 +5,10 @@
  * This source code is licensed under the BSD-style license found in the
  * LICENSE file in the root directory of this source tree. An additional grant
  * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @flow
  */
+
 'use strict';
 
 const log = require('../util/log').out('bundle');
@@ -17,15 +20,26 @@ const path = require('path');
 const saveAssets = require('./saveAssets');
 const defaultAssetExts = require('../../packager/defaults').assetExts;
 
-import type RequestOptions from './types.flow';
+import type {RequestOptions, OutputOptions} from './types.flow';
+import type {ConfigT} from '../util/Config';
 
 function saveBundle(output, bundle, args) {
   return Promise.resolve(
     output.save(bundle, args, log)
   ).then(() => bundle);
 }
 
-function buildBundle(args, config, output = outputBundle, packagerInstance) {
+function buildBundle(
+  args: OutputOptions & {
+    assetsDest: mixed,
+    entryFile: string,
+    resetCache: boolean,
+    transformer: string,
+  },
+  config: ConfigT,
+  output = outputBundle,
+  packagerInstance,
+) {
   // This is used by a bazillion of npm modules we don't control so we don't
   // have other choice than defining it as an env variable here.
   process.env.NODE_ENV = args.dev ? 'development' : 'production';