Add dummy dart:html library for documentation.

lib/html/doc/interface/SVGMarkerElement.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 SVGMarkerElement
+interface SVGMarkerElement extends SVGElement, SVGLangSpace, SVGExternalResourcesRequired, SVGStylable, SVGFitToViewBox {
+
+  static final int SVG_MARKERUNITS_STROKEWIDTH = 2;
+
+  static final int SVG_MARKERUNITS_UNKNOWN = 0;
+
+  static final int SVG_MARKERUNITS_USERSPACEONUSE = 1;
+
+  static final int SVG_MARKER_ORIENT_ANGLE = 2;
+
+  static final int SVG_MARKER_ORIENT_AUTO = 1;
+
+  static final int SVG_MARKER_ORIENT_UNKNOWN = 0;
+
+  /** @domName SVGMarkerElement.markerHeight */
+  final SVGAnimatedLength markerHeight;
+
+  /** @domName SVGMarkerElement.markerUnits */
+  final SVGAnimatedEnumeration markerUnits;
+
+  /** @domName SVGMarkerElement.markerWidth */
+  final SVGAnimatedLength markerWidth;
+
+  /** @domName SVGMarkerElement.orientAngle */
+  final SVGAnimatedAngle orientAngle;
+
+  /** @domName SVGMarkerElement.orientType */
+  final SVGAnimatedEnumeration orientType;
+
+  /** @domName SVGMarkerElement.refX */
+  final SVGAnimatedLength refX;
+
+  /** @domName SVGMarkerElement.refY */
+  final SVGAnimatedLength refY;
+
+  /** @domName SVGMarkerElement.setOrientToAngle */
+  void setOrientToAngle(SVGAngle angle);
+
+  /** @domName SVGMarkerElement.setOrientToAuto */
+  void setOrientToAuto();
+}