Addition of just the entry points for OES_sample_shading extension. Bug: angleproject:3587 Change-Id: I7ef5ceb846d130c2d1e0b4ea7dcbe92452b5d7d3 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2444212 Commit-Queue: Mohan Maiya <m.maiya@samsung.com> Reviewed-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shahbaz Youssefi <syoussefi@chromium.org>
