Polymer: Make paper-spinner-styles TrustedTypes compliant.

Eventually this should be patched in the upstream repo, tracked at
https://github.com/PolymerElements/paper-spinner/issues/102.

Bug: 1098690
Change-Id: I14c8703ccb5f369750692b3b672b5371c7f4f12f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3970100


Commit-Queue: John Lee <johntlee@chromium.org>
Auto-Submit: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: John Lee <johntlee@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1062384}