Used a script to find test files that have more ES2_OPENGL() invocations
than ES2_VULKAN(), and added ES2_VULKAN() to those.  There may be false
negatives.

Bug: angleproject:1578
Change-Id: I938eb3571c909879e9276b355a9f1d324880f99a
Reviewed-on: https://chromium-review.googlesource.com/c/1324350Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>