Remove trailing commas from Blink IDLs

Source/core/workers/AbstractWorker.idl

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 14 matching lines @@
  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 [
     NoInterfaceObject,
     ActiveDOMObject,
-    EventTarget,
+    EventTarget
 ] interface AbstractWorker {
 
     attribute EventListener onerror;
 
     void addEventListener(DOMString type,
                           EventListener listener,
                           optional boolean useCapture);
     void removeEventListener(DOMString type,
                              EventListener listener,
                              optional boolean useCapture);
     [RaisesException] boolean dispatchEvent(Event evt);
 };