There was no need to use FlyString for error messages, and it just
caused a bunch of churn since these strings typically only existed
during the lifetime of the error.
(cherry picked from commit 175f3febb8037a440d4ead7347d3266ee3d345e1;
minorly amended to fix conflict in WebSocket.cpp due to serenity
not having the adapter class removal in LadybirdBrowser/ladybird#1671)
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.
