Ref #4509

%TypedArray%.prototype properties

…

• read-only %TypedArray%.prototype properties
  • work as expected if the receiver is backed by an immutable ArrayBuffer
  • %TypedArray%.prototype.filter throws a TypeError if the receiver constructs an instance backed by an immutable ArrayBuffer, after determining contents
  • %TypedArray%.prototype.map throws a TypeError if the receiver constructs an instance backed by an immutable ArrayBuffer, after validating that callback is callable but before invoking it
  • %TypedArray%.prototype.slice throws a TypeError if the receiver constructs an instance backed by an immutable ArrayBuffer, after coercing bounds

Note that the "Cover existing read-only TypedArray methods" commit is large but mostly mechanical, the others are small and actually specific to immutable ArrayBuffer.