Pen down does not draw on Edge or Safari

[fsih]

Expected Behavior

Pen down (without a move after) should draw to the stage

Actual Behavior

Pen down does not draw

Steps to Reproduce

0. Add pen extension
1. Set pen size to large number
2. Click pen down

Operating System and Browser

Windows Edge

[paulkaplan]

From the other issue:

Interesting, this is a real disagreement in the canvas spec between webkit and chrome/firefox. This jsfiddle shows that safari doesn't draw zero-length paths, despite the cap style: https://jsfiddle.net/bqt1cf2p/8/

We could nudge the second x/y pair for the drawPoint function in renderer/src/PenSkin by a microscopic amount, offsetting one coordinate by 1e-5 seems to do the trick. Since it is canvas coordinates as far as I can tell, that should be visually identical.

[paulkaplan]

@cwillisf could you weigh in on the best way to fix this? should I do a + 1e-5 to the drawPoint function? Are there other possible problems with that?