Revert "Roll gn from 4a8016dc3915 to 3d0d3445f67d"

This reverts commit a9cf3d0380.

Reason for revert: Suspected cause of tree closure

Original change's description:
> Roll gn from 4a8016dc3915 to 3d0d3445f67d
>
> https://gn.googlesource.com/gn.git/+log/4a8016dc3915..3d0d3445f67d
>
> 2025-03-03 digit@google.com Remove obsolete debug checks.
>
> If this roll has caused a breakage, revert this CL and stop the roller
> using the controls here:
> https://autoroll.skia.org/r/gn-chromium-autoroll
> Please CC dpranke@chromium.org,dpranke@google.com,thakis@chromium.org on the revert to ensure that a human
> is aware of the problem.
>
> To file a bug in Chromium: https://bugs.chromium.org/p/chromium/issues/entry
>
> To report a problem with the AutoRoller itself, please file a bug:
> https://issues.skia.org/issues/new?component=1389291&template=1850622
>
> Documentation for the AutoRoller is here:
> https://skia.googlesource.com/buildbot/+doc/main/autoroll/README.md
>
> Tbr: dpranke@chromium.org,thakis@chromium.org
> Change-Id: I8a7c466813762555d3acda1bcf7472c79c63f8e4
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6317990
> Bot-Commit: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
> Commit-Queue: chromium-autoroll <chromium-autoroll@skia-public.iam.gserviceaccount.com>
> Cr-Commit-Position: refs/heads/main@{#1427178}

No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: Ia94dcf017556889e0c2b6eb6d752ce10b46cc98c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6318234
Commit-Queue: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Steven Luong <stluong@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1427187}

DEPS

@@ -503,7 +503,7 @@ vars = {
   'libcxx_revision':       '7f8b68f91ca8b192375f5e71cd81fb3ed9650ef3',
 
   # GN CIPD package version.
-  'gn_version': 'git_revision:3d0d3445f67d91be25ffdc9ba9b352b9af9cf07e',
+  'gn_version': 'git_revision:4a8016dc391553fa1644c0740cc04eaac844121e',
 
   # ninja CIPD package.
   'ninja_package': 'infra/3pp/tools/ninja/',