swift

e57d5ac8 - [Serialization] If an override is dynamic, missing the base decl is OK

[Serialization] If an override is dynamic, missing the base decl is OK ...specifically `@objc dynamic`, that is. This is one case where we /know/ that the override does not depend on the base in any way---any attributes have already been propagated down, and there's no vtable entry. This is especially important for properties, which have no recovery if their accessors can't be deserialized. rdar://50827914 (cherry picked from commit 2d3872a0768193246e42579d5dd964b5e7b3bd32)