Remove WebThread code violating dependency rules from blink/public

blink/public can't depend on internal blink code but luckily
the code that was violating this was unused so it could just be
deleted.

Bug: 800764

Change-Id: Id487e43362931677e93e15d736e7e74922103be0
Reviewed-on: https://chromium-review.googlesource.com/c/1301522
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Daniel Bratell <bratell@opera.com>
Cr-Commit-Position: refs/heads/master@{#603369}
1 file changed