May in Servo: user scripts, mp4 compat, blackboxing in DevTools, and more!

Servo 0.3.0 contains all of the changes we landed in May, which came out to 391 commits (March: 534). For security fixes, see § Security . We’ve shipped several new web platform features: ‘font-kerning: none’ ( @simonwuelker , #44634 ) ‘font-variant-east-asian’ ( @simonwuelker , #44989 ) ‘font-variant-ligatures’ ( @simonwuelker , #44903 ) ‘font-variant-numeric’ ( @simonwuelker , #44950 ) ‘font-variant-position’ (