Show lint messages in deleted files on the left-hand side of the change

Summary:
See PHI416. If you raise a lint message in a deleted file, we don't render any text on the right hand side so the message never displays.

This is occasionally still legitimate/useful, e.g. to display a "don't delete this file" message. At least for now, show these messages on the left.

Test Plan: Posted a lint message on a deleted file via `harbormaster.sendmessage`, viewed revision, saw file expand with synthetic inline for lint.

Differential Revision: https://secure.phabricator.com/D19171

src/applications/differential/controller/DifferentialChangesetViewController.php

@@ -390,10 +390,20 @@ final class DifferentialChangesetViewController extends DifferentialController {
       return array();
     }
 
+    $change_type = $changeset->getChangeType();
+    if (DifferentialChangeType::isDeleteChangeType($change_type)) {
+      // If this is a lint message on a deleted file, show it on the left
+      // side of the UI because there are no source code lines on the right
+      // side of the UI so inlines don't have anywhere to render. See PHI416.
+      $is_new = 0;
+    } else {
+      $is_new = 1;
+    }
+
     $template = id(new DifferentialInlineComment())
-        ->setChangesetID($changeset->getID())
+      ->setChangesetID($changeset->getID())
-        ->setIsNewFile(1)
+      ->setIsNewFile($is_new)
-        ->setLineLength(0);
+      ->setLineLength(0);
 
     $inlines = array();
     foreach ($messages as $message) {