selection of which name records to keep in the subset method.

elements and serialize method

string

https://github.com/harfbuzz/harfbuzz/issues/1633#issuecomment-485764140

Something's phishy about hb_sorted_array_t<>.  Can't get it work nicely with
change I'm making.  Ugh..

To check for assignment overflows.

still doesn't work with vscode

Let's see if bots happy.

Not sure where else we can use these.  Mm.  Maybe in hb_invoke().