- Don't pass 'verify' since it's now the default
- Update tests where diagnostics changed in a correct way to pass 'on' instead
- Delete compiler_scale/explicit_requirements_perf.swift since it's not testing anything with the requirement machine
Within the compiler, we use the term "layout constraint" for any
constraint that affects the layout of a type parameter that has that
constraint. However, the only user-visible constraint is "AnyObject",
and calling that a layout constraint is confusing. Drop the term
"layout" from diagnostics.
Fixes rdar://problem/35295372.
Because of the way we modeled the 'class' constraint in Swift <= 4, we
allowed both 'class' and 'AnyObject' to be specified on a protocol,
even in Swift 4 when they became equivalent. Recent refactoring
started rejecting such code; allow it now.
Fixes rdar://problem/34496151.
