Web MIDI: clean up on MIDIPort and MIDIErrorCallback

Source/modules/webmidi/MIDIPort.idl

 /*
  * Copyright (C) 2013 Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 10 matching lines @@
  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY 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.
  */
 
-// FIXME: IDL generator doesn't support readonly enum yet.
-// See also, http://crbug.com/234925
-//enum MIDIPortType {
-//    "input",
-//    "output"
-//};
+enum MIDIPortType {
+    "input",
+    "output"
+};
 
 [
     ActiveDOMObject,
     EventTarget
 ] interface MIDIPort {
     readonly attribute DOMString id;
     readonly attribute DOMString manufacturer;
     readonly attribute DOMString name;
-    readonly attribute DOMString type;
+    readonly attribute MIDIPortType type;
     readonly attribute DOMString version;
 
     attribute EventListener ondisconnect;
 
     // EventTarget interface
     void addEventListener(DOMString type,
                           EventListener listener,
                           optional boolean useCapture);
     void removeEventListener(DOMString type,
                              EventListener listener,
                              optional boolean useCapture);
     [RaisesException] boolean dispatchEvent(Event event);
 };