Ensure next and orderedNext are null for slots in HashSlotMap.

[aardvark179]

Slot next and orderedNext in HashSlotMap

When an embedded slot map is promoted to being a HashSlotMap the slots are placed in the new map, but there next and orderedNext fields are not nulled, and nothing in the HashSlotMap code touches those fields. This can lead to slots holding on to an unexpected set of resources via the orderedNext chain which was built by EmbeddedSlotMap.

This PR copies the slots rather than reusing them, and sets the next and orderedNext fields to null on the copies, and sizes the linked hash map to match the number of slots being inserted on promotion to avoid unnecessary internal reallocations during this process.

[gbrail]

This is a great catch -- thanks for your thorough testing. I'll check it out and get to merging this soon.

[gbrail]

Thanks for fixing this!