Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/Float64Array.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 Float64Array
-interface Float64Array extends ArrayBufferView, List<num> default _TypedArrayFactoryProvider {
-
-  Float64Array(int length);
-
-  Float64Array.fromList(List<num> list);
-
-  Float64Array.fromBuffer(ArrayBuffer buffer, [int byteOffset, int length]);
-
-  static final int BYTES_PER_ELEMENT = 8;
-
-  /** @domName Float64Array.length */
-  final int length;
-
-  /** @domName Float64Array.setElements */
-  void setElements(Object array, [int offset]);
-
-  /** @domName Float64Array.subarray */
-  Float64Array subarray(int start, [int end]);
-}