Fix a HunkParser typo, "identcal" -> "identical"

Summary: See rP3f8eccdaec8f85933bfea6ce5348bde25ced0489.

Test Plan: Read carefully.

Reviewers: amckinley, avivey

Reviewed By: avivey

Subscribers: avivey

Differential Revision: https://secure.phabricator.com/D20499

src/applications/differential/parser/DifferentialHunkParser.php

@@ -791,7 +791,7 @@ final class DifferentialHunkParser extends Phobject {
     // of the lines, and these copies truly weren't any different.
     //
     // When lines are aligned and marked identical, but they're not actually
-    // identcal, we now mark them as changed. The rest of the processing will
+    // identical, we now mark them as changed. The rest of the processing will
     // figure out how to render them appropritely.
 
     $new = $this->getNewLines();