Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/AudioBufferSourceNode.dartdoc

-// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-// WARNING:
-//   This file contains documentation that is merged into the real source.
-//   Do not make code changes here.
-
-/// @domName AudioBufferSourceNode
-interface AudioBufferSourceNode extends AudioSourceNode {
-
-  static final int FINISHED_STATE = 3;
-
-  static final int PLAYING_STATE = 2;
-
-  static final int SCHEDULED_STATE = 1;
-
-  static final int UNSCHEDULED_STATE = 0;
-
-  /** @domName AudioBufferSourceNode.buffer */
-  AudioBuffer buffer;
-
-  /** @domName AudioBufferSourceNode.gain */
-  final AudioGain gain;
-
-  /** @domName AudioBufferSourceNode.loop */
-  bool loop;
-
-  /** @domName AudioBufferSourceNode.looping */
-  bool looping;
-
-  /** @domName AudioBufferSourceNode.playbackRate */
-  final AudioParam playbackRate;
-
-  /** @domName AudioBufferSourceNode.playbackState */
-  final int playbackState;
-
-  /** @domName AudioBufferSourceNode.noteGrainOn */
-  void noteGrainOn(num when, num grainOffset, num grainDuration);
-
-  /** @domName AudioBufferSourceNode.noteOff */
-  void noteOff(num when);
-
-  /** @domName AudioBufferSourceNode.noteOn */
-  void noteOn(num when);
-}