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

sdk/lib/_internal/pub_generated/test/get/git/unlock_if_incompatible_test.dart

+// Copyright (c) 2012, 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.
+
+library pub_tests;
+
+import '../../descriptor.dart' as d;
+import '../../test_pub.dart';
+
+main() {
+  initConfig();
+  integration(
+      'upgrades a locked Git package with a new incompatible ' 'constraint',
+      () {
+    ensureGit();
+
+    d.git('foo.git', [d.libDir('foo'), d.libPubspec('foo', '0.5.0')]).create();
+
+    d.appDir({
+      "foo": {
+        "git": "../foo.git"
+      }
+    }).create();
+
+    pubGet();
+
+    d.dir(
+        packagesPath,
+        [d.dir('foo', [d.file('foo.dart', 'main() => "foo";')])]).validate();
+
+    d.git(
+        'foo.git',
+        [d.libDir('foo', 'foo 1.0.0'), d.libPubspec("foo", "1.0.0")]).commit();
+
+    d.appDir({
+      "foo": {
+        "git": "../foo.git",
+        "version": ">=1.0.0"
+      }
+    }).create();
+
+    pubGet();
+
+    d.dir(
+        packagesPath,
+        [d.dir('foo', [d.file('foo.dart', 'main() => "foo 1.0.0";')])]).validate();
+  });
+}