No additional wait

Author: calumma-robert

GoogleSignIn/Future.cs

@@ -71,7 +71,6 @@ internal Future(FutureAPIImpl<T> impl) {
     /// <param name="tcs">Tcs.</param>
     internal IEnumerator WaitForResult(TaskCompletionSource<T> tcs) {
       yield return new WaitUntil(() => !Pending);
-      yield return null;
       if (Status == GoogleSignInStatusCode.CANCELED) {
         tcs.SetCanceled();
       } else if (Status == GoogleSignInStatusCode.SUCCESS ||
@@ -85,7 +84,6 @@ internal IEnumerator WaitForResult(TaskCompletionSource<T> tcs) {
     internal async Task WaitForResultAsync(TaskCompletionSource<T> tcs)
     {
       while (Pending) await Task.Yield();
-      await Task.Yield();
       if (Status == GoogleSignInStatusCode.CANCELED) {
         tcs.SetCanceled();
       } else if (Status == GoogleSignInStatusCode.SUCCESS ||