Fully transitive const is not necessary

[Walter Bright]

Janice Caron wrote:
> ...which raises an interesting point. Can "synchronized" be used on a
> const object? What about an invariant object?

"No" for an invariant object, because there is no point to locking 
something that is invariant. Since an invariant can be implicitly cast 
to const, that means it can't be allowed for const, either.