Intent to ship: Atomics.waitAsync

[Daniel Minor]

As of Firefox 143, I intend to enable Atomics.waitAsync by default on all platforms. It is currently available in all builds, but disabled by default and controlled by the `javascript.options.experimental.javascript.options.atomics_wait_async` preference. Atomics.waitAsync allows verifying that a shared memory location in a TypedArray contains a specified value, for more details see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Atomics/waitAsync.

The proposal reached Stage 4 of the TC39 process in May 2023, V8 shipped their implementation in Chrome 87, and Safari shipped in 16.4.

Bug to turn on by default: https://bugzilla.mozilla.org/show_bug.cgi?id=1884148

Standard: https://tc39.es/ecma262/multipage/structured-data.html#sec-atomics.waitasync

[Daniel Minor]

Just to note that Atomics.waitAsync still has not shipped, we encountered a test failure in a test that was not previously being run, see https://bugzilla.mozilla.org/show_bug.cgi?id=1980271 for more details.

[Daniel Minor]

This ended up shipping in Firefox 145.