This reverts commit e70f6aa6.

Reason for revert: dEQP failures:
dEQP.EGL/functional_get_frame_timestamps_rgb565_no_depth_no_stencil
dEQP.EGL/functional_get_frame_timestamps_rgb565_no_depth_stencil
dEQP.EGL/functional_hdr_metadata_cta861_3
dEQP.EGL/functional_hdr_metadata_smpte2086
dEQP.EGL/functional_mutable_render_buffer_basic
dEQP.EGL/functional_swap_buffers_with_damage_resize_after_swap_buffer_age_clear
dEQP.EGL/functional_swap_buffers_with_damage_resize_after_swap_buffer_age_clear_clear
dEQP.EGL/functional_swap_buffers_with_damage_resize_after_swap_buffer_age_render
dEQP.EGL/functional_swap_buffers_with_damage_resize_before_swap_buffer_age_clear
dEQP.EGL/functional_swap_buffers_with_damage_resize_before_swap_buffer_age_clear_clear
dEQP.EGL/functional_swap_buffers_with_damage_resize_before_swap_buffer_age_render

Original change's description:
> ANGLE_platform_angle_device_context_volatile_* extensions
>
> Change from Kimmo Kinnunen downstream:
> https://bugs.webkit.org/show_bug.cgi?id=216106
>
> Add two extensions for EAGL and CGL backends to declare the
> underlying platform context being "volatile". It means that
> the thread-global current context is being modified behind
> ANGLE. If ANGLE context is marked volatile for a particular
> API, it will sync the underlying context for every EGL
> function that needs the context. Most intuitive use is
> for the client to call eglMakeCurrent before calling any
> gl function if the client knowns the platform state might
> be dirty.
>
> Implement eglReleaseThread for EAGL and CGL backends.
> Releasing thread will unset the platform current context.
>
> Fix a bug of omitting EGL_ANGLE_device_eagl from being
> advertised.
>
> Bug: angleproject:5104
> Change-Id: I1ec98ad35bc0caada23556ae8697fdef20f65b1a
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2486548
> Commit-Queue: James Darpinian <jdarpinian@chromium.org>
> Reviewed-by: Kenneth Russell <kbr@chromium.org>
> Reviewed-by: Geoff Lang <geofflang@chromium.org>

TBR=geofflang@chromium.org,kbr@chromium.org,jdarpinian@chromium.org,jonahr@google.com

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

Bug: angleproject:5104
Change-Id: Ib683625a55a582c39e5a4a0466038cfa6e782e6c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2507260Reviewed-by: Geoff Lang <geofflang@chromium.org>