Fix Diffusion change view header

Summary: See D7162. This was like 99% my fault. Just provide a header; the new ones look pretty reasonable.

Test Plan: Viewed Diffusion change view, no exception.

Reviewers: vrana, chad

Reviewed By: chad

CC: aran

Differential Revision: https://secure.phabricator.com/D7183

src/applications/differential/view/DifferentialChangesetListView.php

@@ -194,11 +194,8 @@ final class DifferentialChangesetListView extends AphrontView {
       ));
     }
 
-    $header = null;
-    if ($this->getTitle() !== null) {
     $header = id(new PHUIHeaderView())
       ->setHeader($this->getTitle());
-    }
 
     $content = phutil_tag(
       'div',

src/applications/diffusion/controller/DiffusionChangeController.php

@@ -37,6 +37,7 @@ final class DiffusionChangeController extends DiffusionController {
     );
 
     $changeset_view = new DifferentialChangesetListView();
+    $changeset_view->setTitle(pht('Change'));
     $changeset_view->setChangesets($changesets);
     $changeset_view->setVisibleChangesets($changesets);
     $changeset_view->setRenderingReferences(