SVG Path - elliptical arc not drawn correctly

Created this test app to demonstrate the issue:
https://github.com/matthewbillienyc/node-canvas-svg-test/

# Node Canvas SVG to PNG issue
So this repo is to show how between `node-canvas` versions `2.0.0-alpha.181` and `2.1.0` a bug with rendering SVG arcs was introduced.

###### Environment Info
```
Ubuntu 18.04
Nodejs 6.11.0
```
###### node-canvas 2.0.0-alpha.18
The png image that is created looks correct.

###### node-canvas 2.1.0
The png image that is created **does not look correct.**

###### SVG data
Here is an [online SVG rendering](https://codepen.io/KFoxder/pen/bZEJmW) of the SVG data below. The offending data is this: `A 10 10 0 1 1 16.499995000000418 10.49000000166666`. Specifically it looks like the `10.49000000166666` in the arc path is what causes it to break.
```svg

```

###### Why is it breaking? Great question!

I am not 100% sure. But we spent some time looking into by comparing all the [commits](https://github.com/Automattic/node-canvas/compare/586b395afb4a7...a5921f6#diff-d52111b9458a13e196dab8299f822c29R2509) between `2.0.0-alpha.18` and `2.1.0`. You will see that it looks like this Pull Request ([`1288: Adapt to V8 7.0`](https://github.com/Automattic/node-canvas/pull/1288)) is the offending change. More specifically I believe it is [these lines in CanvasRenderingContext2d.cc](https://github.com/Automattic/node-canvas/blob/master/src/CanvasRenderingContext2d.cc#L2813-L2826) that caused the breaking of the arc path.