Remove title() from TimelineModel.Record

title is a presentation entity and shouldn't be exposed on model record. TimelineUIUtils should be used to retrieve it.

BUG=361045
R=loislo@chromium.org

Review URL: https://codereview.chromium.org/336183005

git-svn-id: svn://svn.chromium.org/blink/trunk@176503 bbb929c8-8fbe-4397-9dbb-9b2b20218538