The trace-events will have a high overhead when turned on, but they are in a disabled-by-default category.

As long as the off overhead is negligible, this CL allows us to understand the behavior of V8 rather than its performance at the moment.

BUG=v8:5089

Review-Url: https://codereview.chromium.org/2052523002
Cr-Commit-Position: refs/heads/master@{#36909}