This CL makes --trace-maps available in the default build by disabling
certain expensive/intrusive features.

This is an intermediate step to be able to write proper tests for --trace-maps
and the new map-processor.

Change-Id: Ib6a8fc9c77796c106d3af9d741d48abe6c6b9099
Reviewed-on: https://chromium-review.googlesource.com/734648Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48891}