Remove explicit interface versions of dartdoc files.

lib/html/doc/interface/SVGGlyphRefElement.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 SVGGlyphRefElement
-interface SVGGlyphRefElement extends SVGElement, SVGURIReference, SVGStylable {
-
-  /** @domName SVGGlyphRefElement.dx */
-  num dx;
-
-  /** @domName SVGGlyphRefElement.dy */
-  num dy;
-
-  /** @domName SVGGlyphRefElement.format */
-  String format;
-
-  /** @domName SVGGlyphRefElement.glyphRef */
-  String glyphRef;
-
-  /** @domName SVGGlyphRefElement.x */
-  num x;
-
-  /** @domName SVGGlyphRefElement.y */
-  num y;
-}