This reverts commit 7bb6cd63.

Reason for revert: layout tests

Original change's description:
> [coverage] Ship block coverage
> 
> Enables block coverage by default.
> 
> Design doc: http://goo.gl/hSJhXn
> Tracking bug: http://crbug.com/v8/6000
> 
> Bug: v8:6000
> Change-Id: I8c56474473b60e4707b75dc601b3e88455861a27
> Reviewed-on: https://chromium-review.googlesource.com/583093
> Commit-Queue: Jakob Gruber <jgruber@chromium.org>
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#46898}

NOTRY=true
TBR=yangguo@chromium.org,jgruber@chromium.org

Change-Id: I51d6f13d3ad0d2d2262bdd8d67135931cbc27032
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: v8:6000
Reviewed-on: https://chromium-review.googlesource.com/588789Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46923}