DevTools: Regression: After clicking on ">>" sign in sections Dev tools,Flickering list seen

BUG=317558
R=vsevik@chromium.org

Review URL: https://codereview.chromium.org/67493003

git-svn-id: svn://svn.chromium.org/blink/trunk@161903 bbb929c8-8fbe-4397-9dbb-9b2b20218538