Remove trailing commas from Blink IDLs

Source/core/dom/EventException.idl

 /*
  * Copyright (C) 2007 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 10 matching lines @@
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT 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.
  */
 
 // Introduced in DOM Level 2:
 [
-    DoNotCheckConstants,
+    DoNotCheckConstants
 ] exception EventException {
 
     readonly attribute unsigned short   code;
     readonly attribute DOMString        name;
     readonly attribute DOMString        message;
 
     // Override in a Mozilla compatible format
     [NotEnumerable] DOMString toString();
 
     // EventExceptionCode
     const unsigned short UNSPECIFIED_EVENT_TYPE_ERR = 0;
     const unsigned short DISPATCH_REQUEST_ERR = 1;
 };