Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/MutationEvent.dartdoc

Index: lib/html/doc/interface/MutationEvent.dartdoc
diff --git a/lib/html/doc/interface/MutationEvent.dartdoc b/lib/html/doc/interface/MutationEvent.dartdoc
deleted file mode 100644
index 269e6f0d0983e1164c7570e3a469b91037c1d334..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/MutationEvent.dartdoc
+++ /dev/null
@@ -1,35 +0,0 @@
-// 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 MutationEvent
-interface MutationEvent extends Event {
-
-  static final int ADDITION = 2;
-
-  static final int MODIFICATION = 1;
-
-  static final int REMOVAL = 3;
-
-  /** @domName MutationEvent.attrChange */
-  final int attrChange;
-
-  /** @domName MutationEvent.attrName */
-  final String attrName;
-
-  /** @domName MutationEvent.newValue */
-  final String newValue;
-
-  /** @domName MutationEvent.prevValue */
-  final String prevValue;
-
-  /** @domName MutationEvent.relatedNode */
-  final Node relatedNode;
-
-  /** @domName MutationEvent.initMutationEvent */
-  void initMutationEvent(String type, bool canBubble, bool cancelable, Node relatedNode, String prevValue, String newValue, String attrName, int attrChange);
-}