Workaround for unsupported non-scaling-stroke in Edge

[nponeccop]

Currently lines get thicker with zoom. Works in FF and Chrome including mobile.

[streamcode9]

Maybe we should zoom stroke width? Something like:

strokeWidth = 1 / scale

[nponeccop]

It is only a partial workaround as the problem is that the scale is non-uniform - the lines get thick horizontally but thin vertically. Probably we need to combine stroke width adjustment with path regeneration when zoom changes much.

I think this issue is of low priority though.