This is a reland of 21c0d77e

Original change's description:
> [async] Optimize await and AsyncFromSyncIterator
> 
> 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}

Cq-Include-Trybots: luci.chromium.try:linux_chromium_headless_rel;master.tryserver.blink:linux_trusty_blink_rel
Change-Id: Ifa5b2fb8b2fb84b635b2dc1b6455d6aaf154cbfd
Reviewed-on: https://chromium-review.googlesource.com/1106977
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53900}