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

sdk/lib/_internal/pub_generated/test/barback/utils.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS d.file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../lib/src/exit_codes.dart' as exit_codes;
 import '../test_pub.dart';
 
 /// Runs separate integration tests for "pub build", "pub serve", and
@@ skipping 14 matching lines @@
     buildError = error;
 
     assert(serveError == null);
     serveError = error;
   }
 
   // Usage errors also print the usage, so validate that.
   var buildExpectation = buildError;
   var serveExpectation = serveError;
   if (exitCode == exit_codes.USAGE) {
-    buildExpectation = allOf(
-        startsWith(buildExpectation), contains("Usage: pub build"));
-    serveExpectation = allOf(
-        startsWith(serveExpectation), contains("Usage: pub serve"));
+    buildExpectation =
+        allOf(startsWith(buildExpectation), contains("Usage: pub build"));
+    serveExpectation =
+        allOf(startsWith(serveExpectation), contains("Usage: pub serve"));
   }
 
   integration("build fails $description", () {
-    schedulePub(args: ["build"]..addAll(args),
+    schedulePub(
+        args: ["build"]..addAll(args),
         error: buildExpectation,
         exitCode: exitCode);
   });
 
   integration("build --format json fails $description", () {
-    schedulePub(args: ["build", "--format", "json"]..addAll(args),
-        outputJson: {
-          "error": buildError // No usage in JSON output.
-        },
-        exitCode: exitCode);
+    schedulePub(args: ["build", "--format", "json"]..addAll(args), outputJson: {
+      "error": buildError // No usage in JSON output.
+    }, exitCode: exitCode);
   });
 
   integration("serve fails $description", () {
-    schedulePub(args: ["serve"]..addAll(args),
+    schedulePub(
+        args: ["serve"]..addAll(args),
         error: serveExpectation,
         exitCode: exitCode);
   });
-}
+}