The promise file is too big so I am splitting it in several CLs.

TNodified:
 * AllocatePromiseReaction
 * AllocatePromiseReactionJobTask
 * AllocatePromiseResolveThenableJobTask
 * CreatePromiseResolvingFunctions
 * CreatePromiseResolvingFunctionsContext
 * CreatePromiseContext

This CL introduces some CASTs that will be deleted once the file is
TNodified in full.

Bug: v8:6949
Change-Id: Ia3006faa5e9fd0e6fa3c58511772857910326532
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1809360
Commit-Queue: Santiago Aboy Solanes <solanes@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63882}