Revert "Use native async/await support in pub."

sdk/lib/_internal/pub_generated/lib/src/barback/barback_server.dart

Index: sdk/lib/_internal/pub_generated/lib/src/barback/barback_server.dart
diff --git a/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart b/sdk/lib/_internal/pub_generated/lib/src/barback/barback_server.dart
similarity index 95%
copy from sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
copy to sdk/lib/_internal/pub_generated/lib/src/barback/barback_server.dart
index f825bd853240a1e4e746bbec31e7552d3fcee567..24658e22592e090fdf4139ee289248bc70c63f1d 100644
--- a/sdk/lib/_internal/pub/lib/src/barback/barback_server.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/barback/barback_server.dart
@@ -51,8 +51,8 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
   /// directory. If [rootDirectory] is omitted, the bound server can only be
   /// used to serve assets from packages' lib directories (i.e. "packages/..."
   /// URLs). If [package] is omitted, it defaults to the entrypoint package.
-  static Future<BarbackServer> bind(AssetEnvironment environment,
-      String host, int port, {String package, String rootDirectory}) {
+  static Future<BarbackServer> bind(AssetEnvironment environment, String host,
+      int port, {String package, String rootDirectory}) {
     if (package == null) package = environment.rootPackage.name;
     return bindServer(host, port).then((server) {
       if (rootDirectory == null) {
@@ -64,8 +64,8 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
     });
   }
 
-  BarbackServer._(AssetEnvironment environment, HttpServer server,
-      this.package, this.rootDirectory)
+  BarbackServer._(AssetEnvironment environment, HttpServer server, this.package,
+      this.rootDirectory)
       : super(environment, server);
 
   /// Converts a [url] served by this server into an [AssetId] that can be
@@ -108,7 +108,8 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
 
     // See if the asset should be blocked.
     if (allowAsset != null && !allowAsset(id)) {
-      return notFound(request,
+      return notFound(
+          request,
           error: "Asset $id is not available in this configuration.",
           asset: id);
     }
@@ -117,8 +118,8 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
       return result;
     }).then((asset) => _serveAsset(request, asset)).catchError((error, trace) {
       if (error is! AssetNotFoundException) throw error;
-      return environment.barback.getAssetById(id.addExtension("/index.html"))
-          .then((asset) {
+      return environment.barback.getAssetById(
+          id.addExtension("/index.html")).then((asset) {
         if (request.url.path.endsWith('/')) return _serveAsset(request, asset);
 
         // We only want to serve index.html if the URL explicitly ends in a
@@ -148,8 +149,9 @@ class BarbackServer extends BaseServer<BarbackServerResult> {
       // running "pub serve" in parallel with another development server. Since
       // "pub serve" is only used as a development server and doesn't require
       // any sort of credentials anyway, this is secure.
-      return response.change(
-          headers: const {"Access-Control-Allow-Origin": "*"});
+      return response.change(headers: const {
+        "Access-Control-Allow-Origin": "*"
+      });
     });
   }