This microbenchmark tests the time at which we find index ranges
in the cache, and how long the call to prepareIndexData might take.
It also verifies we successfully store index ranges in the cache.

BUG=angleproject:956

Change-Id: I0f1b0c00daa73d8e1bcde197d9de80ca229078b7
Reviewed-on: https://chromium-review.googlesource.com/262779Reviewed-by: Geoff Lang <geofflang@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>