R1:33997d43d0ea

Fix undefined index in ManiphestTaskSummaryView

Summary:
Currently, my homepage raises a couple of these:

[13-Mar-2013 06:44:38] WARNING: [pool www] child 27678 said into stderr: "NOTICE: PHP message: [2013-03-13 06:44:38] ERROR 8: Undefined index: at [/INSECURE/devtools/phabricator/src/applications/maniphest/view/ManiphestTaskSummaryView.php:133]"
[13-Mar-2013 06:44:38] WARNING: [pool www] child 27678 said into stderr: "NOTICE: PHP message: #0 ManiphestTaskSummaryView::render() called at…