The latest Pixel drivers require that the GL line raserization emulation
is disabled to rasterize the lines correctly.

Bug: angleproject:2830
Test: dEQP-GLES2.functional.rasterization.primitives.line*
Test: dEQP-GLES2.functional.clipping.line.long_line_clip
Change-Id: I126715e61f44500c00efc7e81044c0a09001d3bb
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/1812177Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>