leafo/lessphp — pull request #407 by AnhNhan (2013-04-08 15:45:41+00:00)
Title: Adding `@viewport` directive and relatives

Hello,
I noticed that when adding something like
```css
@-ms-viewport {
width: device-width;
}
```
to enable responsiveness under Metro IE10 in Snap mode, it got absorbed and sucked up in some Nirvana I don't know about.

I just noticed that they were missing in the block directives, and added them. I also added a few vendor-specific variants that I deemed reasonable (I'm not sure if Gecko dropped vendor prefix already, though).