getDisplayMode() returns null

[fxzjshm]

In this file DragomeGraphics.java, getDisplayMode() returns null.
This causes some codes to fail, for example I got a TypeError (and I cannot catch it). I think this method should return the size of the <canvas>.
Moreover, other functions should return what it should return instead of null.
Thank you for fixing them.

[xpenatan]

I've added this method. If there is any other method you need I'll try to port from gwt or create it if its possible.

[fxzjshm]

OK, thank you very much! I'll test it later this week.