Remove a comment that predates removing analyze()

Summary: This seems to be saying TransProfile + GuardRelaxation didn't work in
analyze().  Should we keep the EvalJitRegionSelector check or not?

Reviewed By: @swtaarrs

Differential Revision: D1651369

Signature: t1:1651369:1415219871:6c35b3497972db8290a9a1cdf98853db0ff59df4
Rename vasm's end instruction to fallthru

Summary: It conflicts with non-member use of end() on STL-style containers.

Reviewed By: @edwinsmith

Differential Revision: D1669397

Signature: t1:1669397:1415620123:5a835c9db286c4f752b75788202bc874265376dc
Simplify ArrayGet on constant arrays

Summary: I saw an IR snippet doing ArrayGets on an array we knew was static.
(Hhbbc also knew, but doesn't constant propagate anything out of minstrs, and
that'd be harder right now.)

Reviewed By: @markw65

Differential Revision: D1654328

Signature: t1:1654328:1414891382:4baf7e0dc880be238aa17b7d1eb43a5cf00f12bc
Fix some bugs in intersecting specialized types

Summary: If you intersect two arrays of different kinds you should always get
bottom, so it was being unnecessarily pessimistic.  If you intersect two
non-exact specialized classes that could be interfaces, you can't return bottom
unless you prove that there's no mutually derived classes.

Reviewed By: @swtaarrs

Differential Revision: D1669253