Revert 149769 &quotRevert 149745 &quotImprove mitigation from r109406 to...&quot

      See bug 238363

> Revert 149745 &quotImprove mitigation from r109406 to reset layout r...&quot
> 
> > Improve mitigation from r109406 to reset layout root in cases when document is getting destroyed.
> > 
> > BUG=209604
> > TEST=No test since it is flaky and will be tracked in a seperate functional bug to analyze why RenderSVGRoot is left as a layout root. Fix tested under ASAN.
> > R=schenney@chromium.org
> > 
> > Review URL: https://codereview.chromium.org/14846011
> 
> TBR=inferno@chromium.org
> 
> Review URL: https://codereview.chromium.org/15005003

TBR=fsamuel@chromium.org

Review URL: https://codereview.chromium.org/15016003

git-svn-id: svn://svn.chromium.org/blink/trunk@149793 bbb929c8-8fbe-4397-9dbb-9b2b20218538