This CL adds a TRACE_EVENT where there is an isolated LOG, a HistogramTimer
or a TimerEvent.

Once we have a d8 tracing controller, all TimerEvents will be removed since
they do not provide an added value over TRACE_EVENTs. HistogramTimers will
remain, but their functionality will be limited to Histograms only.

BUG=v8:4562
LOG=N

Review URL: https://codereview.chromium.org/1707563002

Cr-Commit-Position: refs/heads/master@{#34099}