# HG changeset patch
# User Boris Zbarsky <bzbarsky@mit.edu>
# Date 1520483894 18000
# Node ID e101b0c833ffab505fe916afac194c01f0af37dd
# Parent  7ed8a3893667c0b52a2f7aeaefeb0faecaa81617
Bug 1444004.  Implement Event.prototype.srcElement as an alias for .target, nightly-only.  r=smaug

MozReview-Commit-ID: JhKdc07CVsL

diff --git a/dom/events/Event.cpp b/dom/events/Event.cpp
--- a/dom/events/Event.cpp
+++ b/dom/events/Event.cpp
@@ -239,16 +239,27 @@ Event::GetTarget() const
 
 NS_IMETHODIMP
 Event::GetTarget(nsIDOMEventTarget** aTarget)
 {
   NS_IF_ADDREF(*aTarget = GetTarget());
   return NS_OK;
 }
 
+bool
+Event::IsSrcElementEnabled(JSContext* /* unused */, JSObject* /* unused */)
+{
+  // Not a pref, because that's a pain on workers.
+#ifdef NIGHTLY_BUILD
+  return true;
+#else
+  return false;
+#endif
+}
+
 EventTarget*
 Event::GetCurrentTarget() const
 {
   return mEvent->GetCurrentDOMEventTarget();
 }
 
 void
 Event::ComposedPath(nsTArray<RefPtr<EventTarget>>& aPath)
diff --git a/dom/events/Event.h b/dom/events/Event.h
--- a/dom/events/Event.h
+++ b/dom/events/Event.h
@@ -151,16 +151,17 @@ public:
                                              const nsAString& aType,
                                              const EventInit& aParam,
                                              ErrorResult& aRv);
 
   // Implemented as xpidl method
   // void GetType(nsString& aRetval) {}
 
   EventTarget* GetTarget() const;
+  static bool IsSrcElementEnabled(JSContext* /* unused */, JSObject* /* unused */);
   EventTarget* GetCurrentTarget() const;
 
   void ComposedPath(nsTArray<RefPtr<EventTarget>>& aPath);
 
   uint16_t EventPhase() const;
 
   // xpidl implementation
   // void StopPropagation();
diff --git a/dom/webidl/Event.webidl b/dom/webidl/Event.webidl
--- a/dom/webidl/Event.webidl
+++ b/dom/webidl/Event.webidl
@@ -12,16 +12,18 @@
 
 [Constructor(DOMString type, optional EventInit eventInitDict),
  Exposed=(Window,Worker,System), ProbablyShortLivingWrapper]
 interface Event {
   [Pure]
   readonly attribute DOMString type;
   [Pure]
   readonly attribute EventTarget? target;
+  [Pure, BinaryName="target", Func="Event::IsSrcElementEnabled"]
+  readonly attribute EventTarget? srcElement;
   [Pure]
   readonly attribute EventTarget? currentTarget;
 
   sequence<EventTarget> composedPath();
 
   const unsigned short NONE = 0;
   const unsigned short CAPTURING_PHASE = 1;
   const unsigned short AT_TARGET = 2;