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

sdk/lib/_internal/pub_generated/test/validator/sdk_constraint_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS 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 'dart:async';
 import 'dart:convert';
 
 import 'package:http/http.dart' as http;
 import 'package:http/testing.dart';
 import 'package:path/path.dart' as path;
 import 'package:scheduled_test/scheduled_test.dart';
 
 import '../../lib/src/entrypoint.dart';
 import '../../lib/src/validator.dart';
 import '../../lib/src/validator/sdk_constraint.dart';
 import '../descriptor.dart' as d;
 import '../test_pub.dart';
 import 'utils.dart';
 
 Validator sdkConstraint(Entrypoint entrypoint) =>
-  new SdkConstraintValidator(entrypoint);
+    new SdkConstraintValidator(entrypoint);
 
 main() {
   initConfig();
 
   group('should consider a package valid if it', () {
     integration('has no SDK constraint', () {
       d.validPackage.create();
       expectNoValidationError(sdkConstraint);
     });
 
     integration('has an SDK constraint without ^', () {
-      d.dir(appPath, [
-        d.libPubspec("test_pkg", "1.0.0", sdk: ">=1.8.0 <2.0.0")
-      ]).create();
+      d.dir(
+          appPath,
+          [d.libPubspec("test_pkg", "1.0.0", sdk: ">=1.8.0 <2.0.0")]).create();
       expectNoValidationError(sdkConstraint);
     });
   });
 
-  test("should consider a package invalid if it has an SDK constraint with "
-      "^", () {
-    d.dir(appPath, [
-      d.libPubspec("test_pkg", "1.0.0", sdk: "^1.8.0")
-    ]).create();
-    expect(schedulePackageValidation(sdkConstraint),
+  test(
+      "should consider a package invalid if it has an SDK constraint with " "^",
+      () {
+    d.dir(appPath, [d.libPubspec("test_pkg", "1.0.0", sdk: "^1.8.0")]).create();
+    expect(
+        schedulePackageValidation(sdkConstraint),
         completion(pairOf(anyElement(contains('">=1.8.0 <2.0.0"')), isEmpty)));
   });
 }