[geometry] Name of DOMMatrix and related classes is out of place.

In some contexts, the "DOM" in DOMMatrix feels out of place, for example in
WebGL. Why not call it something like TransformationMatrix,
GraphicalMatrix, Matrix3D, or something more generic like that so the name
is agnostic of where you are using the class. I'm not manipulating DOM
inside of a WebGL context.

I made discussion about this on Discourse:
http://discourse.wicg.io/t/the-name-of-dommatrix-is-out-of-place/1169

- Joe
*/#!/*JoePea