A comment from Robin W's code review on JDK-8167108,
reminded us about a hash table sizing issue:

> 4745 hash_table_size--;
> 4746 hash_table_size |= hash_table_size >> 1;
> ...
>
> This calculation is repeated around line 4922 as well, perhaps put it in a function?

The hash_table_size parameter is currently unused. We were using
a different hash table before that allowed the size to be set.
Unfortunately, that hash table didn't support being freed so we
switched to ResourceHashtable.

We have a project note to come back and update the underlying
hash table to work with dynamic table sizes, but Erik hasn't
had the cycles to do it yet.