This is a reland of c3bd741e
Original change's description:
> Fix "this" value in lazily-parsed module functions.
>
> When preparsing top-level functions in a module, we didn't track
> unresolved variables. Consequently, "this" ended up referencing
> the global "this", which has the wrong value (in a module "this"
> is supposed to be the undefined value).
>
> This patch fixes that. This also lets us stop forcing context
> allocation of all variables in module scopes, which the patch
> takes care of as well.
>
> Bug: chromium:791334
> Change-Id: Ifac1f1adc033f3facfb3d29dd4bca32ee27bffcf
> Reviewed-on: https://chromium-review.googlesource.com/808938
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Reviewed-by: Adam Klein <adamk@chromium.org>
> Reviewed-by: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
> Commit-Queue: Georg Neis <neis@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#50025}

TBR=adamk@chromium.org
TBR=kozyatinskiy@chromium.org

Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel

Bug: chromium:791334
Change-Id: I57acc7b84a345565b36cbb55924fa2ff9b449eec
Reviewed-on: https://chromium-review.googlesource.com/822341
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Georg Neis <neis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50045}