Selection mixin request

[tmazeika]

There doesn't seem to be a mixin for ::selection and ::-moz-selection. An example could be:

@include selection {
  background-color: white;
  color: black;
}

outputs:

::selection {
  background-color: white;
  color: black; }
::-moz-selection {
  background-color: white;
  color: black; }

[tmazeika]

I apologize for some of this Git spam. I've been having trouble with Git :/

[tysongach]

Closing this to move all conversation for this over to the PR you put up.