This exposes BaseAudioContext.listener, which is a container for
parameters related to the configuration of an actual "listener" in 3D
space.
(cherry picked from commit 2a98f2a12d5069a2189fa38b4a7e158d84ee03ec)
That helps to pass more WPT tests
under /webaudio/the-audio-api/the-dynamicscompressornode-interface/ctor-dynamicscompressor.html
(cherry picked from commit f2ed59879f7781019152a18740fc5743cc513016)
For now, this slot is always 0 - (the default value per spec). But
once we start actually processing audio streams this internal slot
should be changed correspondingly.
The spec isn't _super_ clear on how this is meant to be done, but the
way I understand this is that we should simply clamp the returned
'current value' between 'min' and 'max'.
Firefox does not appear to do this clamping, but Chrome does.
This is a simple getter and setter of the OscillatorType enum, with
error checking to not allow 'custom', as that should only be changed
through 'setPeriodicWave()'.
This is still missing a bunch of spec steps to construct the
audio node based on the parameters of the OscillatorNode, but it is at
least enough to construct an object to be able to add a basic test which
can get built upon as more is implemented.
