iOS Simulator Mobile Safari
The iOS simulator does have a Safari browser. Though the Safari browser found on the iOS and OS X are both based on WebKit, they are not exactly identical. So the Safari browser on the iOS is an approximation, not an accurate. 

In addition, the WebKit on OS X is optimized to take advantage of the hardware in current Mac which at present performs faster than the slower hardware in current iOS devices.

I'd suggest that while it's possible to develop using the iOS simulator, it's best to test (for performance and reliability/crash) on the actual iOS device.