Cleanup the use of the DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED macro.

The remaining direct uses of the macro are for
RefCountedGarbageCollectedWillBe... types and cannot be removed yet.

R=oilpan-reviews@chromium.org, sigbjornf@opera.com

Review URL: https://codereview.chromium.org/490863002

git-svn-id: svn://svn.chromium.org/blink/trunk@180644 bbb929c8-8fbe-4397-9dbb-9b2b20218538