WebSockets got moved from the HTML standard to their own, the new
WebSockets Standard (https://websockets.spec.whatwg.org).
Move the IDL file and implementation into a new WebSockets directory and
C++ namespace accordingly.
The single 4000-line WrapperGenerator.cpp file was proving to be a pain
to hack, and was filled with spaghetti, split it into a bunch of files
to lessen the impact of the spaghetti.
Also refactor the whole parser to use a class instead of a giant
function with a million lambdas.