Test for Implement the -webkit-margin-collapse properties correct rendering.

This ref test covers basic collapsing behavior between a box and its container when using -webkit-margin-collapse.

Pink: discard top
Pink: discard bottom
Orange: discard top
Orange: discard bottom
Orange: discard top, discard bottom
Pink: discard top, discard bottom
Orange: separate top, Pink: discard top
Orange: separate bottom, Pink: discard bottom
Orange: discard top, Pink: separate top
Orange: discard bottom, Pink: separate bottom
Orange: separate top, Pink: separate top
Orange: separate bottom, Pink: separate bottom