delete experimental/wasm-skp-debugger

Change-Id: I3188e08f0f451938b16af0f3326607ea4d47ba92
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/519319
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Nathaniel Nifong <nifong@google.com>
18 files changed