TimelinePAnel: remove recordsCounter as an unuseful feature.

BUG=
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/179593003

git-svn-id: svn://svn.chromium.org/blink/trunk@167766 bbb929c8-8fbe-4397-9dbb-9b2b20218538