[geometry] DOMMatrix: Why degrees instead of radians for rotation?

I'm just curious why the spec uses degrees instead of radians for DOMMatrix
rotation methods. Th whole world except for the USA is on the metric system
which uses radians. Plus, radians make more sense and can be easily
described with all of JavaScript's `Math.*` which also use radians, so it
would make sense to use radians in DOMMatrix as well.

If someone really wants to use degrees, they can just use:

```js
function toDegrees (angle) {
  return angle * (180 / Math.PI);
}
```

*/#!/*JoePea