Problem: Crash when generating an RSA key — or serializing one —
whose publicExponent is a typed array whose backing ArrayBuffer has
been detached; for example, by calling transfer() on it.
Cause: Two places with big_integer_from_api_big_integer() reading the
bytes of the backing ArrayBuffer directly. But reading the bytes of a
detached buffer aborts.
Fix: Read the bytes with WebIDL get_buffer_source_copy() — which yields
an empty copy for a detached, or OOB resizable, buffer. The empty array
is already mapped to zero — so generation rejects the zero exponent with
an error, rather than crashing.
Fixes https://github.com/LadybirdBrowser/ladybird/issues/9991
9ffd3e48c3