Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/ImageData.dartdoc

Index: lib/html/doc/interface/ImageData.dartdoc
diff --git a/lib/html/doc/interface/ImageData.dartdoc b/lib/html/doc/interface/ImageData.dartdoc
deleted file mode 100644
index e501a1bb52fd16d3c563f79a2af08a126b0f187d..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/ImageData.dartdoc
+++ /dev/null
@@ -1,20 +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 ImageData
-interface ImageData {
-
-  /** @domName ImageData.data */
-  final Uint8ClampedArray data;
-
-  /** @domName ImageData.height */
-  final int height;
-
-  /** @domName ImageData.width */
-  final int width;
-}