gen_stub: stop cloning Type objects

They are immutable

Author: DanielEScherzer

build/gen_stub.php

@@ -531,6 +531,8 @@ public function equals(SimpleType $other): bool {
     }
 }
 
+// Instances of Type are immutable and do not need to be cloned
+// when held by an object that is cloned
 class Type {
     /** @var SimpleType[] */
     public /* readonly */ array $types;
@@ -3146,13 +3148,6 @@ protected function addModifiersToFieldSynopsis(DOMDocument $doc, DOMElement $fie
             $fieldsynopsisElement->appendChild($doc->createElement("modifier", "readonly"));
         }
     }
-
-    public function __clone()
-    {
-        if ($this->type) {
-            $this->type = clone $this->type;
-        }
-    }
 }
 
 class EnumCaseInfo {