servo: Merge #8355 - Cleanup exit messages and related code (from Ms2ger:Exit); r=nox

Source-Repo: https://github.com/servo/servo
Source-Revision: 9a465c58429547b59b8a6e1258eaaea46bf7e5a2

servo/components/msg/constellation_msg.rs

@@ -517,11 +517,3 @@ impl fmt::Display for PipelineId {
 
 #[derive(Clone, PartialEq, Eq, Copy, Hash, Debug, Deserialize, Serialize, HeapSizeOf)]
 pub struct SubpageId(pub u32);
-
-// The type of pipeline exit. During complete shutdowns, pipelines do not have to
-// release resources automatically released on process termination.
-#[derive(Copy, Clone, Debug, Deserialize, Serialize)]
-pub enum PipelineExitType {
-    PipelineOnly,
-    Complete,
-}