Inherit EventTarget interface instead of duplicating its code

Source/modules/indexeddb/IDBTransaction.idl

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 [
-    ActiveDOMObject,
-    EventTarget
-] interface IDBTransaction {
+    ActiveDOMObject
+] interface IDBTransaction : EventTarget {
 
     // Properties
     readonly attribute DOMString mode;
     readonly attribute IDBDatabase db;
     readonly attribute DOMError error;
 
     // Methods
     [RaisesException] IDBObjectStore objectStore (DOMString name);
     [RaisesException] void abort ();
 
     // Events
     attribute EventListener onabort;
     attribute EventListener oncomplete;
     attribute EventListener onerror;
-    // 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);
 };