swift

ab42f753 - Remove OperandOwnership::NestedBorrow.

Remove OperandOwnership::NestedBorrow. Now that OperandOwnership determines the operand constraints, it doesn't make sense to distinguish between Borrow and NestedBorrow at this level. We want these uses to automatically convert between the nested/non-nested state as the operand's ownership changes. The use does not need to impose any constraint on the ownership of the incoming value. For algorithms that need to distinguish nested borrows, it's still trivial to do so.