Regenerate bindings and tweak some geckolib code for it.
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Regenerate bindings for latest mozilla-central -> stylo merge. I had to tweak somethings in build_gecko.rs to get it to compile with the new bindgen, which then resulted in me having to tweak a bit in glue.rs. Not sure if there's a better way than what I've done here. (Note that the name `RawServoAnimationValueBorrowedList` is a little misleading, since it's naming a Gecko type (nsTArray) with Servo types (ServoAnimationValue pointers) inside it.)
r? @emilio
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