This is a reland of 15d6d7b4.

Original change's description:
> [wasm] Increase code space limit to 1024 MB
>
> Liftoff increases code size, and people start deploying bigger modules.
> Increase the wasm code space limit from 512 MB to 1024 MB to account
> for this.
>
> R=titzer@chromium.org
>
> Bug: chromium:883639, chromium:872684
> Change-Id: I3a2ca29d456635f7f3aa1daef5fa2b0249dc1645
> Reviewed-on: https://chromium-review.googlesource.com/1226971
> Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
> Reviewed-by: Ben Titzer <titzer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#56003}

TBR=titzer@chromium.org

Bug: chromium:883639, chromium:872684
Change-Id: I54461d2a5f32eeaf90c71768eb9f37223dd5ebb6
Reviewed-on: https://chromium-review.googlesource.com/1233256Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56025}