Revise to be delta on proposed Immutable ArrayBuffers

[erights]

https://github.com/tc39/proposal-immutable-arraybuffer , which is now at Stage 2, has overlapping goals. As discussed with @Jack-Works , the remaining functionality of this proposal that goes beyond Immutable ArrayBuffers could be rephrased as a delta assuming that Immutable ArrayBuffers happens first.

[Jack-Works]

I have added an agenda item to Feb 2025 meeting for this