Enabled GL_KHR_no_error added end2end tests for it
Note that GL_KHR_no_error can only be enabled by setting the EGL
attribute currently. Context flags are not currently supported.

Bug: angleproject:1280
Test: angle_end2end_tests --gtest_filter=ContextNoErrorTest.*
Change-Id: Ib5c73b8e284e3e4e5f800750ad6fcbef77be4285
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2068899Reviewed-by: Mohan Maiya <m.maiya@samsung.com>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>