Return safe HTML from all render()

Summary:
This is pretty brutal and it adds some `phutil_safe_html()`.
But it is a big step in the right direction.

Test Plan: None.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T2432

Differential Revision: https://secure.phabricator.com/D4905

src/infrastructure/diff/view/PhabricatorInlineSummaryView.php

@@ -15,7 +15,7 @@ final class PhabricatorInlineSummaryView extends AphrontView {
 
   public function render() {
     require_celerity_resource('inline-comment-summary-css');
-    return $this->renderHeader().$this->renderTable();
+    return hsprintf('%s%s', $this->renderHeader(), $this->renderTable());
   }
 
   private function renderHeader() {