Find all the usages of `--enable-experimental-feature` or
`--enable-upcoming-feature` in the tests and replace some of the
`REQUIRES: asserts` to use `REQUIRES: swift-feature-Foo` instead, which
should correctly apply to depending on the asserts/noasserts mode of the
toolchain for each feature.
Remove some comments that talked about enabling asserts since they don't
apply anymore (but I might had miss some).
All this was done with an automated script, so some formatting weirdness
might happen, but I hope I fixed most of those.
There might be some tests that were `REQUIRES: asserts` that might run
in `noasserts` toolchains now. This will normally be because their
feature went from experimental to upcoming/base and the tests were not
updated.
Form a set of suppressed protocols for a function type based on
the extended flags (where future compilers can start recording
suppressible protocols) and the existing "noescape" bit. Compare
that against the "ignored" suppressible protocol requirements, as we
do for other types.
This involves a behavior change if any client has managed to evade the
static checking for noescape function types, but it's unlikely that
existing code has done so (and it was unsafe anyway).
