Bug 1452569 - Implement Event's returnValue. r=smaug

Add retrunValue into Event's interface

Differential Revision: https://phabricator.services.mozilla.com/D4084

--HG--
extra : moz-landing-system : lando

dom/events/Event.cpp

@@ -1003,6 +1003,20 @@ Event::DefaultPrevented(CallerType aCallerType) const
          aCallerType == CallerType::System;
 }
 
+bool
+Event::ReturnValue(CallerType aCallerType) const
+{
+  return !DefaultPrevented(aCallerType);
+}
+
+void
+Event::SetReturnValue(bool aReturnValue, CallerType aCallerType)
+{
+  if (!aReturnValue) {
+    PreventDefaultInternal(aCallerType == CallerType::System);
+  }
+}
+
 double
 Event::TimeStamp()
 {

dom/events/Event.h

@@ -281,6 +281,10 @@ public:
     return mEvent->mFlags.mMultipleActionsPrevented;
   }
 
+  bool ReturnValue(CallerType aCallerType) const;
+
+  void SetReturnValue(bool aReturnValue, CallerType aCallerType);
+
   bool IsTrusted() const
   {
     return mEvent->IsTrusted();

dom/webidl/Event.webidl

@@ -37,6 +37,8 @@ interface Event {
   [Pure]
   readonly attribute boolean cancelable;
   [NeedsCallerType]
+  attribute boolean returnValue;
+  [NeedsCallerType]
   void preventDefault();
   [Pure, NeedsCallerType]
   readonly attribute boolean defaultPrevented;

testing/web-platform/meta/dom/events/AddEventListenerOptions-passive.html.ini

@@ -1,4 +0,0 @@
-[AddEventListenerOptions-passive.html]
-  [returnValue should be ignored if-and-only-if the passive option is true]
-    expected: FAIL
-

testing/web-platform/meta/dom/events/Event-constructors.html.ini

@@ -1,7 +0,0 @@
-[Event-constructors.html]
-  [Event constructors 2]
-    expected: FAIL
-
-  [Event constructors 3]
-    expected: FAIL
-

testing/web-platform/meta/dom/events/Event-defaultPrevented-after-dispatch.html.ini

@@ -1,4 +0,0 @@
-[Event-defaultPrevented-after-dispatch.html]
-  [Default prevention via returnValue]
-    expected: FAIL
-

testing/web-platform/meta/dom/events/Event-initEvent.html.ini

@@ -1,13 +0,0 @@
-[Event-initEvent.html]
-  [Properties of initEvent(type, true, true)]
-    expected: FAIL
-
-  [Properties of initEvent(type, true, false)]
-    expected: FAIL
-
-  [Properties of initEvent(type, false, true)]
-    expected: FAIL
-
-  [Properties of initEvent(type, false, false)]
-    expected: FAIL
-

testing/web-platform/meta/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
-

testing/web-platform/meta/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
-