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

sdk/lib/_internal/pub_generated/lib/src/validator/dependency_override.dart

Index: sdk/lib/_internal/pub_generated/lib/src/validator/dependency_override.dart
diff --git a/sdk/lib/_internal/pub/lib/src/validator/dependency_override.dart b/sdk/lib/_internal/pub_generated/lib/src/validator/dependency_override.dart
similarity index 80%
copy from sdk/lib/_internal/pub/lib/src/validator/dependency_override.dart
copy to sdk/lib/_internal/pub_generated/lib/src/validator/dependency_override.dart
index a5ce299872d03b0fa383072af5ba94e2aca6bc45..c01b27065d3350b04e22aaf145e1bbff0253a32d 100644
--- a/sdk/lib/_internal/pub/lib/src/validator/dependency_override.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/validator/dependency_override.dart
@@ -13,15 +13,14 @@ import '../validator.dart';
 /// absence thereof).
 class DependencyOverrideValidator extends Validator {
   DependencyOverrideValidator(Entrypoint entrypoint)
-    : super(entrypoint);
+      : super(entrypoint);
 
   Future validate() {
     if (entrypoint.root.dependencyOverrides.isNotEmpty) {
       errors.add(
           'Your pubspec.yaml must not have a "dependency_overrides" field.\n'
-          'This ensures you test your package against the same versions of '
-              'its dependencies\n'
-          'that users will have when they use it.');
+              'This ensures you test your package against the same versions of '
+              'its dependencies\n' 'that users will have when they use it.');
     }
     return new Future.value();
   }