Auto merge of #23000 - jdm:invisible-webgl, r=nox

Make webgl behave better with session history

This prevents the compositor from animating pages that are not actually visible, so pages using webgl do not needlessly impact the performance of the rest of the browser. Additionally, this fixes a problem that was alluded to in [this code](https://github.com/servo/rust-offscreen-rendering-context/blob/b5228c098b889a9806a5f93582903e192b3939ef/src/draw_buffer.rs#L282-L285), causing Servo to delete arbitrary resources when a GC occurred in content that used three.js.

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #22987 and fix #22977 and fix #20934 and fix #20953 and fix #20930 and fix #20950 and fix #20924
- [x] There are tests for these changes

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1 files changed, 11 insertions, 0 deletions

diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 02c4f757875..076204cd0c7 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -2694,6 +2694,13 @@ where
                 },
             };
 
+        if let Some(old_pipeline) = self.pipelines.get(&old_pipeline_id) {
+            old_pipeline.notify_visibility(false);
+        }
+        if let Some(new_pipeline) = self.pipelines.get(&new_pipeline_id) {
+            new_pipeline.notify_visibility(true);
+        }
+
         self.update_activity(old_pipeline_id);
         self.update_activity(new_pipeline_id);
 
@@ -3413,6 +3420,10 @@ where
                 self.notify_history_changed(change.top_level_browsing_context_id);
             },
             Some(old_pipeline_id) => {
+                if let Some(pipeline) = self.pipelines.get(&old_pipeline_id) {
+                    pipeline.notify_visibility(false);
+                }
+
                 // https://html.spec.whatwg.org/multipage/#unload-a-document
                 self.unload_document(old_pipeline_id);
                 // Deactivate the old pipeline, and activate the new one.