This PR adds support for using new JSContext/CurrentRealm to promise and
adds some more helpers that will ease migration to new context model.
Second commit has another demo.
Testing: Covered by WPT
Part of #40600
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Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>
We replace many places that use `SafeJSContext` with `JSContext` and I
also rewrote `is_platform_object_same_origin` to use new `JSContext`.
Unfortunately using wrappers2 in them causes crashes (in handle code),
so I reverted that part in last commit and will fix handles in mozjs
later.
Testing: Refactor, but it is covered by WPT tests
Part of #40600
---------
Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>
