[webauthn] Remove webauthn/idl.html in favor of existing WPTs.

Bug: 664630
Change-Id: Iee24c805527fa5b41cde44547666d1ffa0fb167c
Reviewed-on: https://chromium-review.googlesource.com/910117
Reviewed-by: Mike West <mkwst@chromium.org>
Commit-Queue: Kim Paulhamus <kpaulhamus@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535733}
2 files changed