Update to use CGL crate for mac.
auto merge of #3846 : glennw/servo/cgl, r=metajack
layout: Actually calculate restyle damage while styling.

...oops. Looks like I forgot to do this.

r? @pcwalton
auto merge of #3836 : cgaebel/servo/calculate-restyle-damage, r=pcwalton

...oops. Looks like I forgot to do this.

r? @pcwalton