bug#24784: 26.0.50; JSON strings with utf-16 escape codes

[Drew Adams]

> >> +(defsubst json--decode-utf-16-surrogates (high low)
> >
> > IIRC, there might be no actual benefit from making it a defsubst.
> > If someone could benchmark it, I'd like to see the result.
> 
> I guess it doesn't hurt but I also doubt that it makes a measurable
> difference as utf-16 surrogates are rarely needed.

IMO, we should never, ever use defsubst nowadays.  Unless you can
come up with a REALLY good rationale.

Every time defsubst is used it throws a monkey wrench in the ability
of users to extend and modify Emacs behavior.  And nothing is really
gained.

Just one opinion.