Enable WGSL golden outputs for SkSL folding tests.

This exposes a few remaining tests that generate bad WGSL code.

Change-Id: I6b30ba4d341be9516c7cd048c15167c894d1b236
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/743736
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Auto-Submit: John Stiles <johnstiles@google.com>
Commit-Queue: Kevin Lubick <kjlubick@google.com>
28 files changed