Not working with retina display.

[precz]

Doesn't work when layer is created with detectRetina flag and run on display that have 3 pixel ratio.

Steps to reproduce:

1. Create a layer with detectRetina flag set to true.
2. Run page on device with devicePixelRatio equals 3.
3. Save tiles.
4. Turn off internet connection.
5. Tails are not visible. Tails are available i db.