[VM] Remove obsolete comment.
[VM] Remove obsolete comment.

TEST=none

Bug:47506
Change-Id: I126e077377c8ec27458a4971a8e6c6adfe55b23b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/217443
Reviewed-by: Ben Konyi <67ffcaedcc3dc3d87dddb9627b72dd41756b31b1@google.com>
Commit-Queue: Siva Annamalai <2e618a8cbd7bb6b3d4409061ae407d692a098546@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk