EGL_WINDOW_BIT is now specifically requested for tests that open a
window (those that aren't WithNoFixture).  This makes sure pbuffer-only
configs are not selected for the window.

Additionally, a few WithNoFixture tests are made more robust in the
presence of no-window configs.

In the context of crbug.com/1034840, this means that a subset of end2end
tests would be able to run in a remote desktop environment.  Tested on
Linux/X11 by turning a subset of configs PBUFFER-only.

Bug: chromium:1034840
Change-Id: I09fd149d43d3b865856fe6b9491c5f333f4a2efc
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2378922Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
Reviewed-by: back sept 10 - Jamie Madill <jmadill@chromium.org>
Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org>