This is the last big change necessary to create the
`constellation_traits` crate. This moves the data structure for messages
that originate from the `ScriptThread` and are sent to the
`Contellation` to `constellation_traits`, effectively splitting
`script_traits` in half. Before, `script_traits` was responsible for
exposing the API of both the `ScriptThread` and the `Constellation` to
the rest of Servo.
- Data structures that are used by `ScriptToConstellationMsg` are moved
to `constellation_traits`. The dependency graph looks a bit like this:
`script_layout_interface` depends on `script_traits` depends on
`constellation_traits` depends on `embedder_traits`.
- Data structures that are used in the embedding layer
(`UntrustedNodeAddress`, `CompositorHitTestResult`, `TouchEventResult`
and `AnimationState`) are moved to embedder_traits, to avoid a
dependency cycle between `webrender_traits` and
`constellation_traits`.
- Types dealing with MessagePorts and serialization are moved to
`constellation_traits::message_port`.
Testing: This is covered by existing tests as it just moves types
around.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
Signed-off-by: Martin Robinson <mrobinson@igalia.com>