Auto merge of #22933 - pngai:implement-returnValue-attribute, r=jdm

Implement historical returnValue attribute for Event interface

<!-- Please describe your changes on the following line: -->
Implementation of `returnValue` attribute for Event interface.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #22881 (GitHub issue number if applicable)

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

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components/script/dom/event.rs

@@ -297,6 +297,18 @@ impl EventMethods for Event {
         self.cancelable.get()
     }
 
+    // https://dom.spec.whatwg.org/#dom-event-returnvalue
+    fn ReturnValue(&self) -> bool {
+        self.canceled.get() == EventDefault::Allowed
+    }
+
+    // https://dom.spec.whatwg.org/#dom-event-returnvalue
+    fn SetReturnValue(&self, val: bool) {
+        if !val {
+            self.PreventDefault();
+        }
+    }
+
     // https://dom.spec.whatwg.org/#dom-event-timestamp
     fn TimeStamp(&self) -> u64 {
         self.timestamp

components/script/dom/webidls/Event.webidl

@@ -26,6 +26,7 @@ interface Event {
   readonly attribute boolean bubbles;
   [Pure]
   readonly attribute boolean cancelable;
+  attribute boolean returnValue;  // historical
   void preventDefault();
   [Pure]
   readonly attribute boolean defaultPrevented;

tests/wpt/metadata/dom/events/Event-defaultPrevented.html.ini

@@ -1,4 +0,0 @@
-[Event-defaultPrevented.html]
-  [returnValue should change defaultPrevented if cancelable is true.]
-    expected: FAIL
-

tests/wpt/metadata/dom/events/Event-returnValue.html.ini

@@ -1,19 +0,0 @@
-[Event-returnValue.html]
-  [When an event is created, returnValue should be initialized to true.]
-    expected: FAIL
-
-  [preventDefault() should not change returnValue if cancelable is false.]
-    expected: FAIL
-
-  [returnValue=false should have no effect if cancelable is false.]
-    expected: FAIL
-
-  [preventDefault() should change returnValue if cancelable is true.]
-    expected: FAIL
-
-  [initEvent should unset returnValue.]
-    expected: FAIL
-
-  [returnValue=true should have no effect once the canceled flag was set.]
-    expected: FAIL
-

tests/wpt/metadata/dom/events/EventTarget-dispatchEvent-returnvalue.html.ini

@@ -1,7 +0,0 @@
-[EventTarget-dispatchEvent-returnvalue.html]
-  [Return value of EventTarget.dispatchEvent() affected by preventDefault().]
-    expected: FAIL
-
-  [Return value of EventTarget.dispatchEvent() affected by returnValue.]
-    expected: FAIL
-

tests/wpt/metadata/dom/interfaces.html.ini

@@ -872,9 +872,6 @@
   [Event interface: operation composedPath()]
     expected: FAIL
 
-  [Event interface: attribute returnValue]
-    expected: FAIL
-
   [Event interface: attribute composed]
     expected: FAIL
 
@@ -884,9 +881,6 @@
   [Event interface: document.createEvent("Event") must inherit property "composedPath()" with the proper type]
     expected: FAIL
 
-  [Event interface: document.createEvent("Event") must inherit property "returnValue" with the proper type]
-    expected: FAIL
-
   [Event interface: document.createEvent("Event") must inherit property "composed" with the proper type]
     expected: FAIL
 
@@ -896,9 +890,6 @@
   [Event interface: new Event("foo") must inherit property "composedPath()" with the proper type]
     expected: FAIL
 
-  [Event interface: new Event("foo") must inherit property "returnValue" with the proper type]
-    expected: FAIL
-
   [Event interface: new Event("foo") must inherit property "composed" with the proper type]
     expected: FAIL
 
@@ -911,9 +902,6 @@
   [Event interface: new CustomEvent("foo") must inherit property "composedPath()" with the proper type]
     expected: FAIL
 
-  [Event interface: new CustomEvent("foo") must inherit property "returnValue" with the proper type]
-    expected: FAIL
-
   [Event interface: new CustomEvent("foo") must inherit property "composed" with the proper type]
     expected: FAIL