This reverts commit 68ac4e43.

Reason for revert: Crashes Chrome GPU process startup on Windows x86
See crbug.com/1168272

Original change's description:
> Add support for building in Flutter Windows UWP configuration
>
> Bug: angleproject:5527
> Change-Id: Idf5a4cbb6f84b24fa2448157cab1b6a3bce4d8be
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2620580
> Reviewed-by: Jamie Madill <jmadill@chromium.org>
> Commit-Queue: Jamie Madill <jmadill@chromium.org>

TBR=geofflang@chromium.org,stuart.morgan@gmail.com,jmadill@chromium.org,james@clarkezone.io

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

Tbr: jmadill@chromium.org
Bug: angleproject:5527, chromium:1168272
Change-Id: Ifb37c8026253c6a7c334d5b6c83018c888a9f51c
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2638572
Commit-Queue: Austin Eng <enga@chromium.org>
Reviewed-by: Austin Eng <enga@chromium.org>