plug-ins: fix warning.

Fix the following warning for missing case values:
> enumeration value ‘WEBKIT_LOAD_REDIRECTED’ not handled in switch
(same for WEBKIT_LOAD_COMMITTED)

plug-ins/help-browser/dialog.c

@@ -1126,6 +1126,10 @@ load_changed (WebKitWebView   *view,
       update_actions ();
       select_index (webkit_web_view_get_uri (view));
       break;
+
+    case WEBKIT_LOAD_REDIRECTED:
+    case WEBKIT_LOAD_COMMITTED:
+      break;
     }
 }