Make it easy to test with different vertex data formats.
Add test cases for all formats.

BUG=angleproject:2405

Change-Id: I147643a0912e97588588e67946ac326ed449cf07
Reviewed-on: https://chromium-review.googlesource.com/1053564
Commit-Queue: Frank Henigman <fjhenigman@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>