Remove core/workers/experimental

These experiments have been rotting for several months. We may want
to see about pushing an API like this in the future, but not soon
enough to justify its continued existence in the repo.

Some similar non-worker task-scheduling experiments were using the
WorkerTaskQueue runtime enabled feature. Rename that flag to
ScriptedTaskQueue to better described the remaining uses.

Bug: 879306, 898050, 928819, 966950, 967066
Change-Id: Ib69898585fb7e31c78c7738e3bb02ede3834e959
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1636224
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Reviewed-by: Yutaka Hirano <yhirano@chromium.org>
Commit-Queue: Nate Chapin <japhet@chromium.org>
Cr-Commit-Position: refs/heads/master@{#665142}
49 files changed