Fix WebAudioModel
Fix WebAudioModel

The TypeScriptification of /webaudio involved changing over some model
functions to using events. I mistakenly dispatched the event itself to
the listeners, whereas what I should have done was to obtain the data
from the event and dispatch *that* instead.

This CL, then, extracts the data from the events in the WebAudioModel
and dispatches it to listeners.

Fixed: 1144522
Change-Id: I7f6df3975bb7d106734e2a6c823bb348416536f0
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/2520828
Reviewed-by: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>
Commit-Queue: Jack Franklin <993fcadce4d04090da2fefd557a0995e7966c8d5@chromium.org>
Auto-Submit: Paul Lewis <8915f5d5c39a08c5a3e8a8d7314756e4580816f9@chromium.org>

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