GitLab

This reverts commit 4af59255.

Reason for revert: broken linux-archive-rel build

Build error is 

Build failure is: ENOENT: no such file or directory, open '/b/s/w/ir/cache/builder/src/out/Release/gen/ui/webui/resources/cr_elements/cr_splitter/cr_splitter.m.js'

Build is here:
https://ci.chromium.org/p/chromium/builders/ci/linux-archive-rel/19235

Original change's description:
> WebUI: Stop auto-generating Polymer 3 version of cr-splitter.
> 
> The Polymer 2 version is not used anymore, therefore no auto-generation
> is necessary and the v3 version can be directly checked in.
> 
> Fixed: 1042545
> Change-Id: I5054477c0b7427f4ec6b760e5da3eac904af2320
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2003114
> Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
> Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
> Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#732590}

TBR=dpapad@chromium.org,rbpotter@chromium.org

Change-Id: I363a778967e7be5fafc11fb1a72cebdd5c8dac16
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2006214Reviewed-by: Aleks Totic <atotic@chromium.org>
Commit-Queue: Aleks Totic <atotic@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732596}