Update azure to remove glfw dependency.
layout: Promote absolute positioning, floatedness, and clearance into
flags to avoid virtual calls.

These were showing up really high in the maze solver profile.
auto merge of #3843 : pcwalton/servo/flagify-display-and-position, r=glennw

These were showing up really high in the maze solver profile.

r? @glennw
auto merge of #3842 : glennw/servo/update-azure, r=mbrubeck
Update layers, opengles to use the new glx bindings.
auto merge of #3845 : glennw/servo/update-layers-opengles, r=metajack
Update to use CGL crate for mac.