This reverts commit e82ab75a.

Reason for revert: crbug.com/1052772

Original change's description:
> Provide default implementation of rx::DisplayEGL
> 
> Will allow to use EGL instead of GLX on X11.
> 
> Meant to be used on modern EGL so it requires the extensions
> EGL_KHR_no_config_context and EGL_KHR_surfaceless_context.
> This keeps the default implementation simple (no pBuffer
> fallback)
> 
> Also provide simple WorkerContextEGL.
> 
> Bug: angleproject:4328
> Change-Id: I825c6998e4a3727a13e533ede3d9fb1820edc804
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2031699
> Commit-Queue: Jamie Madill <jmadill@chromium.org>
> Reviewed-by: Jamie Madill <jmadill@chromium.org>

TBR=geofflang@chromium.org,syoussefi@chromium.org,jonahr@google.com,jmadill@chromium.org,julien.isorce@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: angleproject:4328
Change-Id: I62436cad1e6aae0c5e072acb1dab0bd10b2cf722
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2058952Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Corentin Wallez <cwallez@chromium.org>