thoughtbot/bourbon — pull request #459 by slawaEremin (2014-06-20 11:16:40+00:00)
Title: Аdded support for pixel values ​​for "size" mixin

There is some problem in this case:

$width: 350;
$height: 200;

.wrapper {
@include size($width $height);
}

Sass compiles nothing and don't show any errors, this looks a little bit strange. This fix can help with compiling mixin for every type of value(100, 100px, auto).