Auto merge of #12292 - ConnorGBrewster:runnable_variant, r=KiChjang

Consolidate runnable variants on DOMManipulationTask into a single Runnable variant.

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Consolidates the runnable variants on `DOMManipulationTask` into a single `Runnable` variant.
Also combines `MainThreadRunnable` into the `Runnable` trait.

I plan on filing a few E-Easy issues after this lands to implement `name` on each of the structs that implement `Runnable`.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [ ] These changes fix #__ (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [X] These changes do not require tests because refactoring

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1 files changed, 4 insertions, 6 deletions

diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 05689baac39..8a7fc82f52e 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -200,11 +200,9 @@ impl<T: Runnable + Send> Runnable for CancellableRunnable<T> {
 
 pub trait Runnable {
     fn is_cancelled(&self) -> bool { false }
-    fn handler(self: Box<Self>);
-}
-
-pub trait MainThreadRunnable {
-    fn handler(self: Box<Self>, script_thread: &ScriptThread);
+    fn name(&self) -> &'static str { "generic runnable" }
+    fn handler(self: Box<Self>) {}
+    fn main_thread_handler(self: Box<Self>, _script_thread: &ScriptThread) { self.handler(); }
 }
 
 enum MixedMessage {
@@ -1223,7 +1221,7 @@ impl ScriptThread {
 
         // https://html.spec.whatwg.org/multipage/#the-end step 7
         let handler = box DocumentProgressHandler::new(Trusted::new(doc));
-        self.dom_manipulation_task_source.queue(DOMManipulationTask::DocumentProgress(handler)).unwrap();
+        self.dom_manipulation_task_source.queue(DOMManipulationTask::Runnable(handler)).unwrap();
 
         self.constellation_chan.send(ConstellationMsg::LoadComplete(pipeline)).unwrap();
     }