Bug 276008: fix Help Viewer bustage by removing the unused const XML. rs=Neil

extensions/help/resources/content/help.js

@@ -52,8 +52,6 @@ var helpGlossaryPanel;
 
 // Namespaces
 const NC = "http://home.netscape.com/NC-rdf#";
-const SN = "rdf:http://www.w3.org/1999/02/22-rdf-syntax-ns#";
-const XML = "http://www.w3.org/XML/1998/namespace#"
 const MAX_LEVEL = 40; // maximum depth of recursion in search datasources.
 
 // Resources

toolkit/components/help/content/help.js

@@ -49,8 +49,6 @@ var helpGlossaryPanel;
 
 # Namespaces
 const NC = "http://home.netscape.com/NC-rdf#";
-const SN = "rdf:http://www.w3.org/1999/02/22-rdf-syntax-ns#";
-const XML = "http://www.w3.org/XML/1998/namespace#"
 const MAX_LEVEL = 40; // maximum depth of recursion in search datasources.
 const MAX_HISTORY_MENU_ITEMS = 6;