* Revert "Create FoundationInternals, an internal module to host shared files used by FoundationInternationalization and FoundationEssentials (#101)"
This reverts commit 8f08a649db1f3eb31593cdae7a30c5e95cb614a7.
* Reapply fb718cd3fb9f058a5fd6d736cec9c2b99d6f7dc6 fix to the other restored LockedState
* Create FoundationInternals, an internal module to host shared files used by FoundationInternationalization and FoundationEssentials
- Modules will access FoundationInternals types with `package import FoundationInternals`. This is currently an experimental feature of `AccessLevelOnImport`.
- Move `LockedState` to FoundationInternals and publicize functions needed by other modules.
* rdar://105027055: Do not use as-casts in specializations.
Introduce _specializingCast and use it instead of `as?`-casts inside
if ladders that implement generic specialization.
`as?` invokes undesirable runtime machinery such as bridging checks.
* rdar://105027055: Ensure AttributedString views have properly aligned bounds
* rdar://105027055: Implement index(_:offsetBy:limitedBy:) in AttributedString views
* rdar://107778676 Stop vendoring the Collections package
* rdar://107778676 Fix test expectation
AttributedString.CharacterView needs to round all indices down to the
nearest Character boundary to avoid semantic issues with its
Collection conformance. This means that CharacterView slices can never
start or end in between Character boundaries.
* Remove a stray print statement
