Stop working around issue 7790 in pub.

utils/pub/utils.dart

Index: utils/pub/utils.dart
diff --git a/utils/pub/utils.dart b/utils/pub/utils.dart
index 1ab0bc6cdc1b06e68439de4c78005432171a831d..e605579417e03737af720af397a178cef7321229 100644
--- a/utils/pub/utils.dart
+++ b/utils/pub/utils.dart
@@ -118,26 +118,6 @@ void chainToCompleter(Future future, Completer completer) {
       onError: (e) => completer.completeError(e.error, e.stackTrace));
 }
 
-// TODO(nweiz): remove this when issue 7790 is fixed.
-/// Like [Future.whenComplete], except that [action] may return a [Future]. If
-/// it does, the returned [Future] won't complete until [action]'s [Future]
-/// completes.
-///
-/// The returned [Future] always has the same value as [future].
-Future asyncWhenComplete(Future future, Future action()) {
-  Future futurify(Future future) {
-    if (future != null) return future;
-    return new Future.immediate(null);
-  }
-
-  return future.then((result) => futurify(action()).then((_) => result),
-      onError: (e) {
-    return futurify(action()).then((_) {
-      throw e;
-    });
-  });
-}
-
 // TODO(nweiz): unify the following functions with the utility functions in
 // pkg/http.