Also added TRIANGLE_FAN & LINE_LOOP instanced draws test cases.

Bug: angleproject:2634
Change-Id: I84740a7221ab49710cf23767c81fa2d303aad364
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1919280Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>