Points only optimization doesn't exist for indexing

[MBkkt]

https://github.com/google/s2geometry/blob/master/src/s2/s2region_term_indexer.cc#L213

It looks like same possible for index terms, am I right?

Why do I need other terms (not true_max_level) if query contains only points?

[MBkkt]

da93358

[MBkkt]

#296

[MBkkt]

@smcallis @jmr What do you think?

[jmr]

I don't know the algorithm well enough. Since you already implemented this as part of #296, can you write some tests and convince yourself it works? I can look in more detail next week.

[MBkkt]

Ok!

[smcallis]

I'm not familiar with this one either so I'd need some time to familiarize myself. A test case I can use to look at the performance internally would be helpful.