Fix samples/ffi/http/test/http_test.dart

Bug: https://github.com/dart-lang/sdk/issues/53657
Fixes: https://github.com/dart-lang/sdk/issues/53657
Change-Id: Ib055eca57e6aba9329d94d5113ae59ffbdadf3ae
TEST=samples/ffi/http/test/http_test.dart
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/328683
Reviewed-by: Ryan Macnak <rmacnak@google.com>
Commit-Queue: Liam Appelbe <liama@google.com>

samples/ffi/http/test/http_test.dart

@@ -18,7 +18,11 @@ Future<void> main() async {
 
   test('httpServe', () async {
     final completer = Completer<String>();
-    httpServe((request) => completer.complete(request));
+    httpServe((request) {
+      if (!completer.isCompleted) {
+        completer.complete(request);
+      }
+    });
     final request = await completer.future;
     expect(request, contains('www.example.com'));
   });

samples/samples.status

@@ -15,6 +15,7 @@ ffi/*: SkipByDesign # FFI skips, see ffi.status
 *: Skip # Not yet triaged.
 
 [ $arch != x64 || $compiler != dartk || $system != linux || $hot_reload || $hot_reload_rollback ]
+ffi/http/test/http_test: SkipByDesign
 ffi/sqlite/test/sqlite_test: SkipByDesign # FFI not supported or libsqlite3.so not available.
 
 [ $runtime == d8 || $browser ]