Inherit EventTarget interface instead of duplicating its code

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 f00ed3f1ce8afdae0034b4d73737b257cd02e4cf..e709f70bb379bc7ed9cb30435c21faf4c66a722c 100644
--- a/Source/core/workers/WorkerGlobalScope.idl
+++ b/Source/core/workers/WorkerGlobalScope.idl
@@ -26,10 +26,9 @@
 
 [
     GlobalContext=WorkerGlobalScope,
-    EventTarget,
     CustomToV8,
     DoNotGenerateWrap
-] interface WorkerGlobalScope {
+] interface WorkerGlobalScope : EventTarget {
 
     // WorkerGlobalScope
     [Replaceable] readonly attribute WorkerGlobalScope self;
@@ -41,15 +40,6 @@
     [Custom] void importScripts(/*[Variadic] in DOMString urls */);
     [Replaceable] readonly attribute WorkerNavigator navigator;
 
-    // EventTarget interface
-    void addEventListener(DOMString type, 
-                          EventListener listener, 
-                          optional boolean useCapture);
-    void removeEventListener(DOMString type, 
-                             EventListener listener, 
-                             optional boolean useCapture);
-    [RaisesException] boolean dispatchEvent(Event evt);
-
     // Additional constructors
     attribute URLConstructor webkitURL; // FIXME: deprecate this.
 };