Add SVG interfaces to browser globals

This pull request adds all of the SVG interfaces documented in the [Gecko DOM Reference](https://developer.mozilla.org/en-US/docs/Gecko_DOM_Reference) to the browser global variables collection.

All of these interfaces are implemented in the latest versions of all major browsers, and should probably be defined in the browser global variables list.

**Technical Documentation**

* [SVG Interfaces (Gecko DOM Reference)](https://developer.mozilla.org/en-US/docs/Gecko_DOM_Reference#SVG_interfaces)
* [Scalable Vector Graphics 1.1 (W3C)](http://www.w3.org/TR/SVG/)
* [SVG DOM IDL Definitions (W3C)](http://www.w3.org/TR/SVG/idl.html)