Fix for keeping lists structure

javatests/org/chromium/distiller/webdocument/FakeWebDocumentBuilder.java

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.distiller.webdocument;
 
 import org.chromium.distiller.DomUtil;
 
 import com.google.gwt.core.client.JsArray;
 import com.google.gwt.dom.client.Element;
@@ skipping 55 matching lines @@
         documentStringBuilder.append(textNode.getData());
     }
 
     @Override
     public void lineBreak(Node node) {
         documentStringBuilder.append("\n");
     }
 
     @Override
     public void embed(WebElement embed) {}
+
+    @Override
+    public void tag(WebTag tag) {}
 }