Just have all the timing functions return 0 for now.
We can now run the Shynet JS on https://linus.dev/ although the XHR
is rejected by our same-origin policy.
This patch adds a FooPrototype and FooConstructor class for each IDL
interface we generate JS bindings for.
These classes are very primitive and don't do everything they should
yet, but we have to start somewhere. :^)
Work towards #4789