This reverts commit fe50e817.

Reason for revert: Too close to branch point

Original change's description:
> [parser] Tentative: turn on FLAG_preparser_scope_analysis.
> 
> The main motivation is to get bug reports / crashes from Canary.
> 
> This commit is expected to break all kinds of things! The most typical failure
> modes are crashes, CHECK failures and JavaScript executing incorrectly.
> 
> BUG=v8:5516
> 
> Change-Id: Ifa02b420ad4e8eda46002b334bed2665c8ceeeb2
> Reviewed-on: https://chromium-review.googlesource.com/623751
> Reviewed-by: Camillo Bruni <cbruni@chromium.org>
> Commit-Queue: Marja Hölttä <marja@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#47502}

TBR=adamk@chromium.org,marja@chromium.org,cbruni@chromium.org

Change-Id: I98d2d186cbde6e185b05ef0d3460115a654b6b45
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:5516
Reviewed-on: https://chromium-review.googlesource.com/626796Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Marja Hölttä <marja@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47519}