Fake timers in Sinon doesn't work with performance-now

[Saegrov]

We have a use-case where we are using Sinons-fake timers in our unit tests. http://sinonjs.org/releases/v4.0.1/fake-timers/

Sinon (or lolex) hijacks globals like process.hrtime to allow faking time.

Using performance-now with Sinon doesn't work since performance-now keeps a reference to process.hrtime. When Sinon patches the global hrtime, performance-now still keeps a reference to the original hrtime