Fix WebAudio#2240: Align with Web IDL specification

This builds on PR WebAudio#2238 by applying everything done there and also
fixing the bikeshed error about `void` not existing. These are
replaced by `undefined`.

Author: rtoy

expected-errs.txt

@@ -10,9 +10,5 @@ LINE: Can't find the 'destinationNode' argument of method 'AudioNode/disconnect(
 LINE: Can't find the 'destinationNode' argument of method 'AudioNode/disconnect(destinationParam, output)' in the argumentdef block.
 LINE: Can't find the 'input' argument of method 'AudioNode/disconnect(destinationParam, output)' in the argumentdef block.
 LINE: Can't find method '['AudioWorkletProcessor/process(inputs, outputs, parameters))']'.
-LINK ERROR: No 'idl-name' refs found for 'void'.
-<a class="n" data-link-type="idl-name" data-lt="void">void</a>
-LINK ERROR: No 'idl' refs found for 'void'.
-{{void}}
 LINE: No 'idl' refs found for 'process(inputs, outputs, parameters))'.
  ✔  Successfully generated, but fatal errors were suppressed