Re-activate unit tests for user literals.

TODO.txt

@@ -29,4 +29,3 @@
 
 ## Unrelated / other
 - review (and avoid) use of 'clone' keyword
-- what is 'user literal support', why are unit tests skipped?

changelog/userliterals.md

@@ -0,0 +1 @@
+- Re-activated unit tests for user literals, which were previously disabled due to a bug in refactoring to v5.

tests/UnitTests/Compiler/Delimiter/UserLiteralTest.php

@@ -17,11 +17,7 @@ class UserliteralTest extends PHPUnit_Smarty
 {
     public function setUp(): void
     {
-        if (!property_exists('Smarty', 'literals')) {
-            $this->markTestSkipped('user literal support');
-        } else {
-            $this->setUpSmarty(__DIR__);
-        }
+        $this->setUpSmarty(__DIR__);
     }