[worklets] Change WorkerInspectorController to accept a WorkerThread.

This is to allow WorkerInspectorController to work with a ThreadedWorkletGlobalScope as well.

The alternative here is to add the required methods (thread() etc) on WorkerOrWorkletGlobalScope which I don't think is the best approach.

BUG=567358

Review-Url: https://codereview.chromium.org/2171973006
Cr-Commit-Position: refs/heads/master@{#408278}
3 files changed