code: public Content getAllClassesLinkScript(String id) {
          HtmlTree script = HtmlTree.SCRIPT();
          String scriptCode = "<!--" + DocletConstants.NL +
                  "  allClassesLink = document.getElementById(\"" + id + "\");" + DocletConstants.NL +
                  "  if(window==top) {" + DocletConstants.NL +
                  "    allClassesLink.style.display = \"block\";" + DocletConstants.NL +
                  "  }" + DocletConstants.NL +
                  "  else {" + DocletConstants.NL +
                  "    allClassesLink.style.display = \"none\";" + DocletConstants.NL +
                  "  }" + DocletConstants.NL +
                  "  //-->" + DocletConstants.NL;
          Content scriptContent = new RawHtml(scriptCode);
          script.addContent(scriptContent);
          Content div = HtmlTree.DIV(script);
          Content div_noscript = HtmlTree.DIV(getResource("doclet.No_Script_Message"));
          Content noScript = HtmlTree.NOSCRIPT(div_noscript);
          div.addContent(noScript);
          return div;
      }
docs: Get the script to show or hide the All classes link.
  
  @param id id of the element to show or hide
  @return a content tree for the script