Revert "Enable unified garbage collections part two"

This reverts commit 79ffe683c7cc22ab3478b119adcc9b49584bd9e2.

Reason for revert: Speculative revert: lots of garbage-collection related failures on WebKit Linux Trusty ASAN (see https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty%20ASAN/17912)

Original change's description:
> Enable unified garbage collections part two
> 
> This flag overrides the default Blink value for content layer.
> 
> Sheriffs: This is a dry-run of the feature and will be reverted after
> cycling through the waterfall and performance bots.
> 
> Tbr: jochen@chromium.org, lfg@chromium.org
> Bug: 843903
> Change-Id: Ie362301e4874198eb775346d051bf8267837aaf8
> Reviewed-on: https://chromium-review.googlesource.com/c/1320970
> Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
> Reviewed-by: Kentaro Hara <haraken@chromium.org>
> Reviewed-by: Hannes Payer <hpayer@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#606446}

TBR=haraken@chromium.org,hpayer@chromium.org,mlippautz@chromium.org,jochen@chromium.org,lfg@chromium.org

Change-Id: I189aca41c8f8ba11c358a4c15bc7f56591e38196
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 843903
Reviewed-on: https://chromium-review.googlesource.com/c/1328902
Reviewed-by: Patrik Höglund <phoglund@chromium.org>
Commit-Queue: Patrik Höglund <phoglund@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606778}
7 files changed