Auto merge of #25653 - pshaughn:removeonclick, r=jdm

Make nulling out an inline event handler remove it from the list order

Setting a content attribute or IDL attribute to null now removes event handlers like it's supposed to; the removeAttribute case seems to be something deeper which this change doesn't fix.

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- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #25196, but not the related #25652

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- [X] There are tests for these changes

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components/script/dom/eventtarget.rs

@@ -404,9 +404,15 @@ impl EventTarget {
         });
 
         match idx {
-            Some(idx) => {
-                entries[idx].listener =
-                    EventListenerType::Inline(listener.unwrap_or(InlineEventListener::Null));
+            Some(idx) => match listener {
+                // Replace if there's something to replace with,
+                // but remove entirely if there isn't.
+                Some(listener) => {
+                    entries[idx].listener = EventListenerType::Inline(listener);
+                },
+                None => {
+                    entries.remove(idx);
+                },
             },
             None => {
                 if let Some(listener) = listener {