Method setSlot

Fleece/Integration/MCollection.hh:76–82

        }

        void setSlot(MValue *newSlot, MValue *oldSlot) {
            if (_usuallyTrue(_slot == oldSlot)) {
                _slot = newSlot;
                if (!newSlot)
                    _parent = nullptr;
            }
        }

        void setContext(MContext *ctx) {
            if (_usuallyTrue(ctx != _context)) {