Inspector uses event name only for enqueue* events and doesn't really need name for other events.

BUG=v8:5738
R=jgruber@chromium.org,gsathya@chromium.org
TBR=yangguo@chromium.org

Review-Url: https://codereview.chromium.org/2628173005
Cr-Commit-Position: refs/heads/master@{#42339}