Revert of Insist on a Blink GC on RenderViewImpl unit test teardowns.

Revert of Insist on a Blink GC on RenderViewImpl unit test teardowns. (patchset #1 id:1 of https://codereview.chromium.org/1621823004/ )

Reason for revert:
Rolling this one out, going with https://codereview.chromium.org/1645923002/ 's approach instead.

Original issue's description:
> Insist on a Blink GC on RenderViewImpl unit test teardowns.
> 
> Without it, flaky LSan reports are a risk, depending on GC timing and
> on tests allowing posted GC tasks to be processed before many of them
> abruptly clear posted messages as part of their operation.
> 
> R=haraken
> TBR=jochen
> BUG=
> 
> Committed: https://crrev.com/ca438fc0e1e6731a6bebee4e298f8e5dd7da44fa
> Cr-Commit-Position: refs/heads/master@{#371169}

TBR=haraken@chromium.org,jochen@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=

[sof, 2016-01-28 12:39:39]

Created Revert of Insist on a Blink GC on RenderViewImpl unit test teardowns.

[commit-bot: I haz the power, 2016-01-28 12:40:06]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1649753002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1649753002/1

[sof, 2016-01-28 12:44:42]

The CQ bit was unchecked by sigbjornf@opera.com

[sof, 2016-01-28 12:46:42]

Stopped; taking this through CQ will just create lag & ASan flakes while doing
so. Unnecessary overhead.

Reverting it as part of https://codereview.chromium.org/1645923002/ instead.