Add workaround for Chrome pointerLock bug that caused jumpiness in mouse nav

I reported the [issue](https://code.google.com/p/chromium/issues/detail?id=386791&thanks=386791&ts=1403213097) to the Chromium team.  This should get us through until it is fixed.

@kadst43 @BrettASwift @scottnc27603 @davideaster @AmbientOSX @ajiraffe would you mind reviewing?