The blit refactoring mislabeled one shader as GL_RED instead of
GL_RED_INTEGER.

BUG=angleproject:1076
TEST= dEQP-GLES3.functional.fbo.render.shared_depth_stencil.*

Change-Id: I262b218c72d955a88a2d2c00b470d6a4f3568451
Reviewed-on: https://chromium-review.googlesource.com/286774Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Tested-by: Jamie Madill <jmadill@chromium.org>