Implement onunhandledrejection / onrejectionhandled events

Source/core/frame/WindowEventHandlers.idl

Index: Source/core/frame/WindowEventHandlers.idl
diff --git a/Source/core/frame/WindowEventHandlers.idl b/Source/core/frame/WindowEventHandlers.idl
index e329309c80556f728604447626855cc2ab8faa63..5c4131796f2f4c7778ed86249f0b1dc9fe3e421f 100644
--- a/Source/core/frame/WindowEventHandlers.idl
+++ b/Source/core/frame/WindowEventHandlers.idl
@@ -46,6 +46,8 @@
     attribute EventHandler onpagehide;
     attribute EventHandler onpageshow;
     attribute EventHandler onpopstate;
+    [RuntimeEnabled=PromiseRejectionEvent] attribute EventHandler onrejectionhandled;

[philipj_slow, 2015/06/16 14:58:03]

Here and in WorkerGlobalScope.idl, can you put the added things in a section at
the bottom called "Unhandled Rejection Tracking" or similar that links to
https://github.com/domenic/unhandled-rejections-browser-spec? (To make it easier
to track which bits come from which spec.)

[jochen (gone - plz use gerrit), 2015/06/17 07:57:53]

done

     attribute EventHandler onstorage;
+    [RuntimeEnabled=PromiseRejectionEvent] attribute EventHandler onunhandledrejection;
     attribute EventHandler onunload;
 };