swift

741244e1 - [region-isolation] Split in the type system SILIsolationInfo that has been merged and those that haven't.

[region-isolation] Split in the type system SILIsolationInfo that has been merged and those that haven't. Specifically, I introduced a new composition type called SILDynamicMergedIsolationInfo that just contains a SILIsolationInfo. Importantly, whenever one merges a SILIsolationInfo with another SILIsolationInfo, one gets back a SILDynamicMergedIsolationInfo. The reason why I am doing this is that we drop nonisolated(unsafe) when merging so I want to ensure that parts of the code that use merging (where the dropping occurs) and normal SILIsolationInfo where we do not want to merge is distinguished.