(Navigator) Use a link label instead of a menu item to download more dicts

The previous setup failed to ensure that the menu item and preference did not return to a valid state and is very non-standard.. Opening a webpage from a dropdown list.. Fuck that shit.

navigator/components/preferences/content/pref-content.js

@@ -188,11 +188,5 @@ function InitLanguageMenu() {
 }
 
 function SelectLanguage(aTarget) {
-  if (aTarget.value != "more-cmd")
-    gLastSelectedLang = aTarget;
-  else {
-    openDictionaryList();
-    if (gLastSelectedLang)
-      document.getElementById("languageMenuList").selectedItem = gLastSelectedLang;
-  }
+  gLastSelectedLang = aTarget;
 }

navigator/components/preferences/content/pref-content.xul

@@ -150,8 +150,7 @@
                   preference="spellchecker.dictionary">
           <menupopup onpopupshowing="InitLanguageMenu();">
             <!-- dynamic content populated by JS -->
-            <menuseparator/>
-            <menuitem value="more-cmd" label="&moreDictionaries.label;"/>
+            <menuseparator hidden="true"/>
           </menupopup>
         </menulist>
         <spring flex="1"/>
@@ -170,6 +169,11 @@
           </menupopup>
         </menulist>
       </hbox>
+      <separator class="thin"/>
+      <label id="moreDictionaries"
+       class="text-link"
+       value="&moreDictionaries.label;"
+       onclick="openDictionaryList()"/>
     </groupbox>
 
     <vbox class="box-padded" align="start">