TimelinePanel: clear button doesn't clear overview panel in Frames and FlameChart modes.

We had no guarantees that framesModel gets RecordsCleared event earlier than views that use it.
Looks like direct call is more straightforward solution.

BUG=
R=pfeldman@chromium.org

Review URL: https://codereview.chromium.org/164753007

git-svn-id: svn://svn.chromium.org/blink/trunk@167235 bbb929c8-8fbe-4397-9dbb-9b2b20218538