swift

590d3353 - Frontend: Introduce an alias for the IsolatedAny experimental feature.

Frontend: Introduce an alias for the IsolatedAny experimental feature. To preserve compatibility with older compilers that do not allow `IsolatedAny` to be enabled in production compilers, use an alias experimental feature when building the stdlib (`IsolatedAny2`). Also, add `@_allowFeatureSuppression(IsolatedAny)` in a couple spots it was forgotten. Partially resolves rdar://125138945