Timeline: Move presentation selector from TimelineOverviewPane to TimelinePanel

As a preliminary step I need to move presentationSelector out from TimelineOverviewPanel.
After that I'd be able to reuse the overview panel in TimelinePanel2.

BUG=326121
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/108353002

git-svn-id: svn://svn.chromium.org/blink/trunk@163429 bbb929c8-8fbe-4397-9dbb-9b2b20218538