Test more environments

[mathiasbynens]

I want to add this to the README:

## Support

Regenerate has been tested in at least Chrome 27-29, Firefox 3-22, Safari 4-6, Opera 10-12, IE 6-10, Node.js v0.10.0, Narwhal 0.3.2, RingoJS 0.8-0.9, and Rhino 1.7RC4.

Let’s make it happen! Environments to test:

• Chrome 27-29
• Firefox 3-22
• Safari 4-6
• Opera 10-12
• IE 6-10
• Node.js v0.10.0
• Narwhal 0.3.2
• RingoJS 0.8-0.9
• Rhino 1.7RC4
• PhantomJS

The test suite is pretty damn slow, but hey. Testing Rhino can take up to 90 seconds on my machine. Narwhal: 150 seconds.