Implement onunhandledrejection / onrejectionhandled events

Source/core/workers/WorkerGlobalScope.idl

Index: Source/core/workers/WorkerGlobalScope.idl
diff --git a/Source/core/workers/WorkerGlobalScope.idl b/Source/core/workers/WorkerGlobalScope.idl
index 7d631e36919b33bfb5bdc3064f986653aed54693..1d3f4d5c13a61e502bfe9b06435a2d5fbd000252 100644
--- a/Source/core/workers/WorkerGlobalScope.idl
+++ b/Source/core/workers/WorkerGlobalScope.idl
@@ -46,6 +46,11 @@
     // Console API (non-standard but widely implemented in some form)
     // https://developer.chrome.com/devtools/docs/console-api
     [Replaceable] readonly attribute WorkerConsole console;
+
+    // Unhandled Promise Rejection Events
+    // https://github.com/domenic/unhandled-rejections-browser-spec
+    [RuntimeEnabled=PromiseRejectionEvent] attribute EventHandler onrejectionhandled;
+    [RuntimeEnabled=PromiseRejectionEvent] attribute EventHandler onunhandledrejection;
 };
 
 WorkerGlobalScope implements WindowBase64;