DevTools: remove TimelineModel.Events.RecordAdded event

All recorded events are processed at once. It doesn't make sense to process them one by one now that we use tracing backend and there are no live updates while the profile is being recorded.

BUG=361045

Review URL: https://codereview.chromium.org/710113002

git-svn-id: svn://svn.chromium.org/blink/trunk@185047 bbb929c8-8fbe-4397-9dbb-9b2b20218538