December in Servo: multiple windows, proxy support, better caching, and more!

Servo 0.0.4 and our December nightly builds now support multiple windows ( @mrobinson , @mukilan , #40927 , #41235 , #41144 )! This builds on features that landed in Servo’s embedding API last month . We’ve also landed support for several web platform features, both old and new: ‘contrast-color()’ in CSS color values ( @webbeef , #41542 ) partial support