makeImmutableArrayBufferInternal = realBuffer => {
  const result = { __proto__: ImmutableArrayBufferInternalPrototype };
  buffers.set(result, realBuffer);
  return /** @type {ArrayBuffer} */ (/** @type {unknown} */ (result));
}
Emulates the encapsulated `ImmutableArrayBufferInternal` class constructor
from the original except this function takes the `realBuffer` which its
result encapsulates. Security demands that this result has exclusive access
to the `realBuffer` it is given, which its callers must ensure.

@param {ArrayBuffer} realBuffer
@returns {ArrayBuffer}