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

sdk/lib/_internal/pub_generated/test/serve/watch_removed_file_test.dart

Index: sdk/lib/_internal/pub_generated/test/serve/watch_removed_file_test.dart
diff --git a/sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart b/sdk/lib/_internal/pub_generated/test/serve/watch_removed_file_test.dart
similarity index 75%
copy from sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart
copy to sdk/lib/_internal/pub_generated/test/serve/watch_removed_file_test.dart
index 55ff576d655fb58ac7ce09318a3465a6aee83840..222a4e31b6957bd9bd1786087cf5ced61953ff2d 100644
--- a/sdk/lib/_internal/pub/test/serve/watch_removed_file_test.dart
+++ b/sdk/lib/_internal/pub_generated/test/serve/watch_removed_file_test.dart
@@ -15,18 +15,15 @@ import 'utils.dart';
 main() {
   initConfig();
   integration("stop serving a file that is removed", () {
-    d.dir(appPath, [
-      d.appPubspec(),
-      d.dir("web", [
-        d.file("index.html", "body")
-      ])
-    ]).create();
+    d.dir(
+        appPath,
+        [d.appPubspec(), d.dir("web", [d.file("index.html", "body")])]).create();
 
     pubServe();
     requestShouldSucceed("index.html", "body");
 
-    schedule(() => deleteEntry(
-        path.join(sandboxDir, appPath, "web", "index.html")));
+    schedule(
+        () => deleteEntry(path.join(sandboxDir, appPath, "web", "index.html")));
 
     waitForBuildSuccess();
     requestShould404("index.html");