do not show installed add-ons in disco promos (bug 643617)

apps/discovery/templates/discovery/modules/collection.html

@@ -13,7 +13,8 @@
     </hgroup>
     <ul class="addons">
       {% for addon in addons %}
-        <li{% if addon.type == amo.ADDON_PERSONA %} class="persona-feature"{% endif %}>
+        <li data-guid="{{ addon.guid }}"
+            {% if addon.type == amo.ADDON_PERSONA %}class="persona-feature"{% endif %}>
           <a href="{{ services_url('discovery.addons.detail', addon.slug,
                                    src='discovery-promo') }}" target="_self">
             {% if addon.type == amo.ADDON_PERSONA %}

media/js/zamboni/discovery_pane.js

@@ -15,6 +15,8 @@ $(document).ready(function(){
         // Store the pane URL so we can link back from the add-on detail pages.
         z.discoStorage.set("url", location);
 
+        hideInstalled();
+
         // Show "Starter Pack" panel only if user has fewer than three extensions.
         if (z.guids.length >= z.MIN_EXTENSIONS) {
             $("#starter").closest(".panel").remove();
@@ -67,7 +69,11 @@ function initSidebar() {
         }
         $("#right-module").replaceWith(data).slideDown("slow");
     });
+}
 
+
+function hideInstalled() {
+    // Do not show installed extensions in the promo modules or sidebar.
     $('li[data-guid]').each(function() {
         var $el = $(this),
             guid = $el.attr('data-guid');