Issue #595 - Implement window.event

This MSIE extension is still technically part of the standard*, although its use is discouraged. This API will also likely never go away based on some comments at this issue on MDN content**.

Note that this uses a different approach for getting the inner window.

* https://dom.spec.whatwg.org/#interface-window-extensions
** https://github.com/mdn/content/issues/21848

Spec PR: https://github.com/whatwg/dom/pull/407
Spec discussion: https://github.com/whatwg/dom/issues/334

Partially based on https://bugzilla.mozilla.org/show_bug.cgi?id=218415

4 files changed, 32 insertions, 1 deletions

diff --git a/dom/base/FragmentOrElement.cpp b/dom/base/FragmentOrElement.cpp
index 412031f98a..ccfe960cb7 100644
--- a/dom/base/FragmentOrElement.cpp
+++ b/dom/base/FragmentOrElement.cpp
@@ -820,6 +820,10 @@ nsIContent::GetEventTargetParent(EventChainPreVisitor& aVisitor)
   aVisitor.mCanHandle = true;
   aVisitor.mMayHaveListenerManager = HasListenerManager();
 
+  if (IsInShadowTree()) {
+    aVisitor.mItemInShadowTree = true;
+  }
+
   // Don't propagate mouseover and mouseout events when mouse is moving
   // inside chrome access only content.
   bool isAnonForEvents = IsRootOfChromeAccessOnlySubtree();
diff --git a/dom/base/nsGlobalWindow.cpp b/dom/base/nsGlobalWindow.cpp
index c6b35a9bf0..01023f3a2d 100644
--- a/dom/base/nsGlobalWindow.cpp
+++ b/dom/base/nsGlobalWindow.cpp
@@ -907,7 +907,8 @@ nsPIDOMWindow<T>::nsPIDOMWindow(nsPIDOMWindowOuter *aOuterWindow)
   mOuterWindow(aOuterWindow),
   // Make sure no actual window ends up with mWindowID == 0
   mWindowID(NextWindowID()), mHasNotifiedGlobalCreated(false),
-  mMarkedCCGeneration(0), mServiceWorkersTestingEnabled(false)
+  mMarkedCCGeneration(0), mServiceWorkersTestingEnabled(false),
+  mEvent(nullptr)
  {}
 
 template<class T>
@@ -5244,6 +5245,16 @@ nsGlobalWindow::SetOpener(JSContext* aCx, JS::Handle<JS::Value> aOpener,
 }
 
 void
+nsGlobalWindow::GetEvent(JSContext* aCx, JS::MutableHandle<JS::Value> aRetval)
+{
+  if (mEvent) {
+    Unused << nsContentUtils::WrapNative(aCx, mEvent, aRetval);
+  } else {
+    aRetval.setUndefined();
+  }
+}
+
+void
 nsGlobalWindow::GetStatusOuter(nsAString& aStatus)
 {
   MOZ_RELEASE_ASSERT(IsOuterWindow());
diff --git a/dom/base/nsGlobalWindow.h b/dom/base/nsGlobalWindow.h
index e42835a0b2..e593890af0 100644
--- a/dom/base/nsGlobalWindow.h
+++ b/dom/base/nsGlobalWindow.h
@@ -845,6 +845,7 @@ public:
   already_AddRefed<nsPIDOMWindowOuter> GetOpener() override;
   void SetOpener(JSContext* aCx, JS::Handle<JS::Value> aOpener,
                  mozilla::ErrorResult& aError);
+  void GetEvent(JSContext* aCx, JS::MutableHandle<JS::Value> aRetval);
   already_AddRefed<nsPIDOMWindowOuter> GetParentOuter();
   already_AddRefed<nsPIDOMWindowOuter> GetParent(mozilla::ErrorResult& aError);
   already_AddRefed<nsPIDOMWindowOuter> GetParent() override;
diff --git a/dom/base/nsPIDOMWindow.h b/dom/base/nsPIDOMWindow.h
index 21eb4cff7f..ffebf6570d 100644
--- a/dom/base/nsPIDOMWindow.h
+++ b/dom/base/nsPIDOMWindow.h
@@ -194,6 +194,10 @@ protected:
   // we have what it takes to do so.
   void MaybeCreateDoc();
 
+  // The event dispatch code sets and unsets this while keeping
+  // the event object alive.
+  nsIDOMEvent* mEvent;
+
 public:
   inline bool IsLoadingOrRunningTimeout() const;
 
@@ -789,6 +793,17 @@ public:
     return mInnerObjectsFreed;
   }
 
+  // Sets the event for window.event. Does NOT take ownership, so
+  // the caller is responsible for clearing the event before the
+  // event gets deallocated. Pass nullptr to set window.event to
+  // undefined. Returns the previous value.
+  nsIDOMEvent* SetEvent(nsIDOMEvent* aEvent)
+  {
+    nsIDOMEvent* old = mEvent;
+    mEvent = aEvent;
+    return old;
+  }
+
   /**
    * Check whether this window is a secure context.
    */