Support for multisampled EGL surfaces was added in
151d5de6 (2017-04-13, "Enable MSAA for texture client buffers")
but the resolve step was missing because it was not needed for
EGL_ANGLE_d3d_texture_client_buffer. However, when using MSAA
with a regular EGL surface then resolving is required to get
an antialiased image.
Please note that the new test case CreateSurfaceWithMSAA does
actually not test the newly added resolve step because the
resolve is performed by the glReadPixels() call there.
So it is rather a general test if MSAA works for EGL surfaces.

TEST=angle_end2end_tests.EGLSurfaceTest.CreateSurfaceWithMSAA

Change-Id: Ieafd6877fa510d5e16c0d9c6872c31fa73efa86c
Reviewed-on: https://chromium-review.googlesource.com/1181138Reviewed-by: Geoff Lang <geofflang@chromium.org>
Reviewed-by: Jamie Madill <jmadill@chromium.org>
Commit-Queue: Geoff Lang <geofflang@chromium.org>