Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/SVGLinearGradientElement.dartdoc

Index: lib/html/doc/interface/SVGLinearGradientElement.dartdoc
diff --git a/lib/html/doc/interface/SVGLinearGradientElement.dartdoc b/lib/html/doc/interface/SVGLinearGradientElement.dartdoc
deleted file mode 100644
index 40dbb3fd02a5a3a862a78030525a10df000d0b5e..0000000000000000000000000000000000000000
--- a/lib/html/doc/interface/SVGLinearGradientElement.dartdoc
+++ /dev/null
@@ -1,23 +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 SVGLinearGradientElement
-interface SVGLinearGradientElement extends SVGGradientElement {
-
-  /** @domName SVGLinearGradientElement.x1 */
-  final SVGAnimatedLength x1;
-
-  /** @domName SVGLinearGradientElement.x2 */
-  final SVGAnimatedLength x2;
-
-  /** @domName SVGLinearGradientElement.y1 */
-  final SVGAnimatedLength y1;
-
-  /** @domName SVGLinearGradientElement.y2 */
-  final SVGAnimatedLength y2;
-}