This reverts commit a9fed96c.

Reason for revert: Serializer test msan failures

Original change's description:
> [parser] Make PreParsedScopeData array-like
> 
> Make PreParsedScopeData a new array-like instance type, which holds its
> child data inline, rather than indirecting to a FixedArray. Should save
> one map word per PreParsedScopeData.
> 
> TBR=jarin@chromium.org
> 
> Bug: chromium:818642
> Change-Id: I72dc21160ed9781ad12b18559468f6cce56886fa
> Reviewed-on: https://chromium-review.googlesource.com/1127055
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Marja Hölttä <marja@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#54349}

TBR=ulan@chromium.org,marja@chromium.org,jarin@chromium.org,leszeks@chromium.org,verwaest@chromium.org

Change-Id: If2f39379bb0bdfca7d36ec1a3ec738519481aa4e
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:818642
Reviewed-on: https://chromium-review.googlesource.com/1131234Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#54354}