These counters were used during the initial implementation to gather
statistics about comparative effectiveness of the two escape analysis
approaches in practice. The counters are not thread-safe and cannot be
used for the analysis any longer as it is now running off main thread.
We deprecate the counters in question in favor of maintaining deferred
statistics until the need for such statistics arises again.

R=bmeurer@chromium.org
BUG=chromium:685942

Review-Url: https://codereview.chromium.org/2667453003
Cr-Commit-Position: refs/heads/master@{#42808}