Update dartc test expectations.

tests/standalone/io/http_server_socket_test.dart

Index: tests/standalone/io/http_server_socket_test.dart
diff --git a/tests/standalone/io/http_server_socket_test.dart b/tests/standalone/io/http_server_socket_test.dart
index 2b835b675b0591ad3768950aa0b5e7636aebfa48..113d75beb25c2a81d65afee7d67b092b87701528 100644
--- a/tests/standalone/io/http_server_socket_test.dart
+++ b/tests/standalone/io/http_server_socket_test.dart
@@ -189,11 +189,11 @@ void testSocketClose() {
 
       if (expectError) {
         ReceivePort port = new ReceivePort();
-        server.onError = (Exception error) {
+        server.onError = (var error) {
           port.close();
         };
       } else {
-        server.onError = (Exception error) {
+        server.onError = (var error) {
           Expect.fail("An error was not expected: $error");
         };
       }