Issue 2672 is tracking the work required to support instanced rendering
with Vulkan backend when the extension VK_EXT_vertex_attribute_divisor
is not present on the device. That work is required to pass the tests
currently marked "FAIL" and GLES 3.0 conformance.

Bug: angleproject:2672
Test: None
Change-Id: I11e3a7a7a9482b4eb3d5f5c7dbf14caec7fff00e
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1790362Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Tobin Ehlis <tobine@google.com>
Commit-Queue: Tim Van Patten <timvp@google.com>