Add support for KeyboardEvent.location attribute

Source/bindings/tests/idls/TestExtendedEvent.idl

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary formstrArg, 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.
  */
 [
     Conditional=TEST,
     ImplementedAs=Event,
-    EnabledAtRuntime=test
+    EnabledAtRuntime=test,
+    ConstructorTemplate=Event
 ] interface TestExtendedEvent
     : TestEvent {
+    [InitializedByEventConstructor] readonly attribute unsigned long location;
+    [ImplementedAs=location, DeprecateAs=KeyboardEventKeyLocation, InitializedByEventConstructor] readonly attribute unsigned long keyLocation;
 };