[less] vendor prefixer mixin

prefix.less

// code from https://github.com/neoascetic/compless

// >> .prefix(box-shadow, 5px);
// -webkit-box-shadow: 5px;
// -moz-box-shadow: 5px;
// -ms-box-shadow: 5px;
// -o-box-shadow: 5px;
// box-shadow: 5px;
//
// >> .prefix(box-shadow, 5px, webkit ms);
// -webkit-box-shadow: 5px;
// -ms-box-shadow: 5px;
// box-shadow: 5px;

@prefixes: webkit moz ms o;

.prefix(@property, @value) {
  .prefix(@property, @value, @prefixes);
}

.prefix(@property, @value, @prefixes) {
  .prefix(@property, @value, @prefixes, 1);
  @{property}: @value;
}

.prefix(@property, @value, @prefixes, @index) when (@index > 0) and (length(@prefixes) >= @index) {
  @prefix: extract(@prefixes, @index);
  -@{prefix}-@{property}: @value;
  .prefix(@property, @value, @prefixes, @index + 1);
}