Revert "Don't enable SwiftShader on Linux platforms if X11 is not available"

This reverts commit 50e4140c1167093ce82de6c6964c95e3379d21f4.

Reason for revert: SwiftShader on ChromeOS issue has been resolved.

Original change's description:
> Don't enable SwiftShader on Linux platforms if X11 is not available
>
> Compilation currently requires <xcb/xcb.h>
>
> Bug: chromium:1266550, b:209030951
> Change-Id: I2d0b6a36fc252bc141aaac26059b4d8f3150f635
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/77300
> Auto-Submit: Austin Eng <enga@chromium.org>
> Reviewed-by: Loko Kung <lokokung@google.com>
> Commit-Queue: Loko Kung <lokokung@google.com>

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

Bug: chromium:1266550, b:209030951
Change-Id: I164d081a49b68a2a217251c902a84690287bd0cc
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/77645
Commit-Queue: Austin Eng <enga@chromium.org>
Auto-Submit: Austin Eng <enga@chromium.org>
Reviewed-by: Loko Kung <lokokung@google.com>
Commit-Queue: Loko Kung <lokokung@google.com>
diff --git a/scripts/dawn_features.gni b/scripts/dawn_features.gni
index 1f5bfaa..d00ab62 100644
--- a/scripts/dawn_features.gni
+++ b/scripts/dawn_features.gni
@@ -34,9 +34,7 @@
 
   # Enables SwiftShader as the fallback adapter. Requires dawn_swiftshader_dir
   # to be set to take effect.
-  # TODO(crbug.com/1266550): Enable on Linux platforms without X11 (e.g. ChromeOS).
-  # Blocked on b/209030951
-  dawn_use_swiftshader = !is_linux || dawn_use_x11
+  dawn_use_swiftshader = true
 }
 
 declare_args() {