Revert of DevTools: Enable antialiasing in the pie chart. (https://codereview.chromium.org/179853002/)

Reason for revert:
This change introduced significant performance penalty - paint time prevents timeline from animating even at 30 fps.

Original issue's description:
> DevTools: Enable antialiasing in the pie chart.
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=168025

TBR=yurys@chromium.org,caseq@chromium.org,alph@chromium.org
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/188053004

git-svn-id: svn://svn.chromium.org/blink/trunk@168566 bbb929c8-8fbe-4397-9dbb-9b2b20218538