Auto merge of #23007 - BartGitHub:remove-pipeline-visibility-checks, r=jdm

Remove pipeline visibility checks

<!-- Please describe your changes on the following line: -->
This includes the following changes/clean-ups:

- Remove ```is_visible``` field from ```Pipeline``` struct
- Remove ```SetVisible``` script message, and related message sending/handling.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22986

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- [x] These changes do not require tests because the issue description states having a passing build is enough for a pull request.

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components/script/dom/htmliframeelement.rs

@@ -397,16 +397,6 @@ impl HTMLIFrameElement {
         }
     }
 
-    pub fn set_visible(&self, visible: bool) {
-        let msg = ScriptMsg::SetVisible(visible);
-        let window = window_from_node(self);
-        window
-            .upcast::<GlobalScope>()
-            .script_to_constellation_chan()
-            .send(msg)
-            .unwrap();
-    }
-
     /// https://html.spec.whatwg.org/multipage/#iframe-load-event-steps steps 1-4
     pub fn iframe_load_event_steps(&self, loaded_pipeline: PipelineId) {
         // TODO(#9592): assert that the load blocker is present at all times when we