This removes the SkRecords::Clear struct and everything that refers to it.
Notice there is nothing actually creating a Clear, which means this is all
dead code.
Now that all ops obey the clip, I don't think we need the weird
inflate-empty-to-epsilon hack for BBH queries.
BUG=skia:
Review URL: https://codereview.chromium.org/835813002
We fix this by rewriting empty queries to very tiny queries, which will certainly
hit ops that span the entire picture (like Clear) and hopefully not much more.
(This doesn't quite work in the full cull rect world if [0,0,ε,ε] doesn't
overlap the picture. Let's cross that bridge when we get there.)
BUG=432991
Review URL: https://codereview.chromium.org/732723004
