search: Remove createResultContainer() hook

It is now unused since the contacts search provider was the only
consumer, so remove it.

https://bugzilla.gnome.org/show_bug.cgi?id=677442

js/ui/search.js

@@ -141,19 +141,6 @@ const SearchProvider = new Lang.Class({
         throw new Error('Not implemented');
     },
 
-    /**
-     * createResultContainer:
-     *
-     * Search providers may optionally override this to render their
-     * results in a custom fashion.  The default implementation
-     * will create a vertical list.
-     *
-     * Returns: An instance of SearchResultDisplay.
-     */
-    createResultContainerActor: function() {
-        return null;
-    },
-
     /**
      * createResultActor:
      * @resultMeta: Object with result metadata

js/ui/searchDisplay.js

@@ -275,10 +275,7 @@ const SearchResults = new Lang.Class({
                                             x_fill: true,
                                             y_fill: true });
         providerBox.add(resultDisplayBin, { expand: true });
-        let resultDisplay = provider.createResultContainerActor();
+        let resultDisplay = new GridSearchResults(provider);
-        if (resultDisplay == null) {
-            resultDisplay = new GridSearchResults(provider);
-        }
         resultDisplayBin.set_child(resultDisplay.actor);
 
         this._providerMeta.push({ provider: provider,