Auto merge of #13531 - wldcordeiro:measure-hashset-mem, r=jdm

Remove ignore-heap-size comment to enable memory measurement on HashSet

Remove the ignore-heap-size comment to enable the memory measurement.

- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #6909

- [x] These changes do not require tests because they just enabled memory measurement

@jdm the build fails, and I'm not so sure why. Assistance please? 😄

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components/script/dom/window.rs

@@ -195,7 +195,6 @@ pub struct Window {
     devtools_chan: Option<IpcSender<ScriptToDevtoolsControlMsg>>,
     /// For sending timeline markers. Will be ignored if
     /// no devtools server
-    #[ignore_heap_size_of = "TODO(#6909) need to measure HashSet"]
     devtools_markers: DOMRefCell<HashSet<TimelineMarkerType>>,
     #[ignore_heap_size_of = "channels are hard"]
     devtools_marker_sender: DOMRefCell<Option<IpcSender<TimelineMarker>>>,