This test was slow enough that running 20k iterations might have been
causing a timeout on the Nexus 5.

Bug: angleproject:2923 
Change-Id: I03f6e95135d8c521e6ef3e81bc9a4b0dfd7f19df
Reviewed-on: https://chromium-review.googlesource.com/c/1310693Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>