mozilla/servo — pull request #1974 by deokjinkim (2014-03-24 13:31:19+00:00)
Title: Implement pseudo-element(before and after)

This change includes implementation of pseudo-element(before and after) for block.
To support pseudo-element, @hyunjunekim inserted additional flow or box for block case.
@hyunjunekim wants to know whether this design is correct or not.
If this design is correct, @hyunjunekim will add more code for float and inline case.