Fix flaky timeouts of socket_ipv6_test.

tests/standalone/io/socket_ipv6_test.dart

Index: tests/standalone/io/socket_ipv6_test.dart
diff --git a/tests/standalone/io/socket_ipv6_test.dart b/tests/standalone/io/socket_ipv6_test.dart
index 54f8a5018b1ea478065c0653c4e44b94e6f4ffa2..d4af582879a28bc99476c9ed82a3e68dc383a37e 100644
--- a/tests/standalone/io/socket_ipv6_test.dart
+++ b/tests/standalone/io/socket_ipv6_test.dart
@@ -56,7 +56,11 @@ void testIPv6toIPv4() {
       server.listen((socket) {
         throw "Unexpected socket";
       });
-      Socket.connect(clientAddr.first, server.port).catchError((e) {
+      Socket.connect(clientAddr.first, server.port).then((socket) {
+        socket.destroy();
+        server.close();
+        asyncEnd();

[kustermann, 2016/12/13 19:36:45]

If you add this then the test is disabled (same below), a wrong dart:io
implementation will pass this test now.

I think retrying is better in these cases (as with the 2 test I've already
fixed).

[Florian Schneider, 2016/12/13 20:23:16]

Done.

+      }).catchError((e) {
         server.close();
         asyncEnd();
       });
@@ -115,10 +119,16 @@ void testIPv4toIPv6_IPV6Only() {
               server.listen((socket) {
                 throw "Unexpected socket";
               });
-              Socket.connect("127.0.0.1", server.port).catchError((error) {
-                server.close();
-                asyncEnd();
-              });
+              Socket.connect("127.0.0.1", server.port)
+                .then((socket) {
+                  socket.destroy();
+                  server.close();
+                  asyncEnd();
+                })
+                .catchError((error) {
+                  server.close();
+                  asyncEnd();
+                });
             });
       });
 }