spec "hosts cannot mutate"

[bakkot]

The essential invariants mean that a nonconfigurable-nonwritable property cannot change once observed, but strictly speaking a host could modify the values in an immutable buffer before they're observed (or if they're observed via the methods on a DataView, to which the essential invariants do not apply).

Per plenary today we should prohibit that, probably by a normative sentence along the lines of "Hosts are not permitted to modify the contents of an immutable ArrayBuffer, even if its contents have not yet been observed by a TypedArray".

[gibson042]

Was this fixed by #44 ("The contents of an immutable ArrayBuffer's Data Block are constrained to be permanently stable, and may not be modified by either ECMAScript code or by other activities inside an implementation or observable by it.")?

[bakkot]

Yup.