Date Slider with two dates and floor is broken

[Head]

Steps to reproduce

Create a slider with two dates and set options.floor

Demo: http://jsfiddle.net/kdysqp1v/2/

[Head]

Not using date objects but date.getTime() for all options works. But it's still a bug if communicated that it should work with dates.

[ValentinH]

Good catch. It needs to be address. I'll try to look into this when I have a bit of time...

[mg1075]

related (?): #614