1918731 - [Outreachy] Add preference for Atomics.pause proposal

Status: NEW

(Core :: JavaScript Engine, task, P2)

Description

[Dan Minor [:dminor]]

The first step to implementing at TC39 proposal in SpiderMonkey is to add a preference for it. This allows for the feature to be enabled or disabled at runtime, which is important, because we don't want to enable a feature by default until we've tested it enough to be confident that it won't cause problems for our users.

This bug is about adding a preference for the Atomics.pause proposal. The steps to do this are:

1. Make sure that you are able to build SpiderMonkey and run the existing tests. There are instructions here. You want to run the jstests, using this command ./mach jstests.
2. Find the section in StaticPrefList.yaml for SpiderMonkey preferences and make a copy of an existing preference. Make sure your copy is inside the #ifdef NIGHTLY_BUILD ... #endif // NIGHTLY_BUILD section, because we only want this to be available on nightly builds to begin with.
3. Change the copy so that the preference name is javascript.options.experimental.atomics_pause and save your changes.
4. Similarly, add an option for the JavaScript shell, by making a copy of this example and changing promise-try to atomics-pause.
5. Make sure you can still build and run the tests.
6. Once the tests all pass for you, you can commit your changes. Your commit message should look like: Bug X - Add preference for Atomics.pause proposal; r=dminor!, where X is the number for this bug.
7. Once you have your changes committed, request review. There are instructions on using phabricator and on getting reviews.