Make phan not complain about Throttle::throttleIdentifier

UserEditTracker::getUserEditCount now allows anonymous users,
but it returns null and phan is aware of this. Suppress this
warning until at least 1.37 is required.

Change-Id: I9962abe08fa31d55421d8bdda23ea0a1c0471a86

includes/Consequences/Consequence/Throttle.php

@@ -203,6 +203,7 @@ class Throttle extends Consequence implements ConsequencesDisablerConsequence {
 				// @codeCoverageIgnoreEnd
 		}
 
+		// @phan-suppress-next-line PhanTypeMismatchReturnNullable Simplify 'editcount' in 1.37+
 		return $identifier;
 	}
 }