Simplify the promise wrapping in await and
%AsyncFromSyncIteratorPrototype%.next/return/throw to reuse the PromiseResolve
primitive. Now await takes 1 tick instead of 3 on the microtask queue.

Change-Id: I7e99b8689eb8fcb09c48915b11c1e06684dc0f1a
Reviewed-on: https://chromium-review.googlesource.com/1090272
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Reviewed-by: Mathias Bynens <mathias@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53853}