I finally fixed streaming audio support (using the Web Audio API). The main streaming audio implementation was done already in Early 2011, using the Mozilla Audio Data API. However, this was Firefox only, and it was removed from Firefox builds in March 2014.
You can easily play all visible functions as sound in the functions panel, here is the realtime play button:
It uses the play options (sample length, rate etc) as the normal play function, but instead of rendering all at once and generating a wav file, it renders on the fly and keeps looping the area, so changes can be heard within a few milliseconds. The play options panel is expanded when you first press any of the play buttons:
So now it is once again possible to play around with this old example: