Roll engine to b3ed79122edd7172327ce415688ef674d6a7fa5d (#7476)

fixes #7433

bin/internal/engine.version

-fc421489b154c6ceb1b8a063541d5a5d4372db6b
+b3ed79122edd7172327ce415688ef674d6a7fa5d

packages/flutter_driver/lib/src/extension.dart

@@ -168,9 +168,6 @@ class _FlutterDriverExtension {
     subscription = _onFrameReady.listen((Duration duration) {
       if (finder.precache()) {
         subscription.cancel();
-        // TODO(goderbauer): Remove workaround for https://github.com/flutter/flutter/issues/7433
-        Timer.run(() {});
-        // end workaround
         completer.complete(finder);
       }
     });

packages/flutter_test/lib/src/binding.dart

@@ -631,8 +631,6 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
       super.handleBeginFrame(rawTimeStamp);
     if (_expectingFrame) {
       assert(_pendingFrame != null);
-      // TODO(yjbanov): workaroud for https://github.com/flutter/flutter/issues/7433
-      Timer.run(() {});  // forces runtime to flush Completer.complete() microtask
       _pendingFrame.complete(); // unlocks the test API
       _pendingFrame = null;
       _expectingFrame = false;