The following features where missing in c2b576d9:

- glGetIntegerv with GL_GPU_DISJOINT_EXT: this is currently impossible
  to query in Vulkan, so 0 is always returned.
- glGetIntegerv with GL_TIMESTAMP_EXT: this is a way to query GPU
  timestamp without performing flushes or waiting for the GPU to finish.
  There is no direct correspondance in Vulkan; it's implemented by
  making a small submission, with no dependency to other submissions, in
  which there is only a timestamp query.

Bug: angleproject:2885
Change-Id: I2341bd610db9084c26b6421c6f8949950ffa4de8
Reviewed-on: https://chromium-review.googlesource.com/c/1299873
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>
Reviewed-by: Geoff Lang <geofflang@chromium.org>