Fix starting Flipper electron in dev mode without default plugins

Summary: yarn start --no-default-plugins currently fails

Reviewed By: nikoant

Differential Revision: D37456367

fbshipit-source-id: 3700055b3b780af4575dd67d50532050d12119df

desktop/scripts/start-dev-server.tsx

@@ -20,7 +20,11 @@ import http from 'http';
 import path from 'path';
 import fs from 'fs-extra';
 import {hostname} from 'os';
-import {compileMain, prepareDefaultPlugins} from './build-utils';
+import {
+  compileMain,
+  prepareDefaultPlugins,
+  prepareHeadlessPlugins,
+} from './build-utils';
 import Watchman from './watchman';
 // @ts-ignore no typings for metro
 import Metro from 'metro';
@@ -441,6 +445,7 @@ function checkDevServer() {
   await prepareDefaultPlugins(
     process.env.FLIPPER_RELEASE_CHANNEL === 'insiders',
   );
+  await prepareHeadlessPlugins();
   await ensurePluginFoldersWatchable();
   const port = await detect(DEFAULT_PORT);
   const {app, server} = await startAssetServer(port);