Process outstanding events before making a new HTTP client request

sdk/lib/io/http_impl.dart

Index: sdk/lib/io/http_impl.dart
diff --git a/sdk/lib/io/http_impl.dart b/sdk/lib/io/http_impl.dart
index bd382bccc28d645f8faae0cee7bfd58069cb6433..4b954ebcaac314203897e2efe65856df54cc8a81 100644
--- a/sdk/lib/io/http_impl.dart
+++ b/sdk/lib/io/http_impl.dart
@@ -1883,7 +1883,7 @@ class _HttpClient implements HttpClient {
           // On error, continue with next proxy.
           .catchError(connect);
     }
-    return connect(new HttpException("No proxies given"));
+    return new Future(() => connect(new HttpException("No proxies given")));
   }
 
   _SiteCredentials _findCredentials(Uri url, [_AuthenticationScheme scheme]) {