[Invalidation tracking] Add trace events for paint invalidations

This patch adds trace events for RO::invalidatePaintIfNeeded and
RO::invalidatePaintUsingContainer so that we can do end-to-end
tracking of what causes repaints to occur. The devtools side isn't
hooked up yet so this patch simply adds the trace events.

A fixme has been added to unify these events with the
blink.invalidations events.

R=kouhei
BUG=410701

Review URL: https://codereview.chromium.org/566813002

git-svn-id: svn://svn.chromium.org/blink/trunk@182539 bbb929c8-8fbe-4397-9dbb-9b2b20218538