timers does not work with Date.now in IE8

[arian]

When you use a polyfill for Date.now, like MooTools or ES5-shim does, the fake timer does not work in (native) IE8.
Probably it's because Sinon.JS feature checks if Date.now is available, but the polyfill is loaded after Sinon.JS is loaded.

Example: http://jsfiddle.net/arian/dhEbb/2/

Don't know if an exception can be made so when useFakeTimer is used, it will check if Date.now exists, or perhaps implementing Date.now anyway (so removing this check: https://github.com/cjohansen/Sinon.JS/blob/master/lib/sinon/util/fake_timers.js#L222), which works for me too.

[cjohansen]

I guess the right thing to do is to check for the existence of Date.now when useFakeTimers is called, as you suggested. In the meantime, you can get around this by loading Sinon after you have loaded the external library that defines Date.now.