Tests: Add --fixed-test-time option Similar to --max-steps-performed, don't do any calibration and just run flat out for a fixed amount of time. Also rename --test-time to --max-trial-time to reflect what the parameter actually does, limiting each trial to a ceiling. Also remove a redundant check in doRunLoop. Test: angle_perftests --fixed-test-time 20 Test: angle_perftests --max-trial-time 2 Bug: angleproject:5935 Change-Id: I854799a734cd6c019399f5a1444b4ef5f659ddf4 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2878937 Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Charlie Lao <cclao@google.com> Commit-Queue: Cody Northrop <cnorthrop@google.com>