Update stubs

Author: actions-user

stubs/ext/spl/AppendIterator.php

@@ -25,7 +25,7 @@ public function current()
     public function next()
     {
     }
-    /** @return int */
+    /** @return int|null */
     public function getIteratorIndex()
     {
     }

stubs/ext/spl/EmptyIterator.php

@@ -3,15 +3,15 @@
 /** @generate-function-entries */
 class EmptyIterator implements \Iterator
 {
-    /** @return void */
+    /** @return mixed */
     public function current()
     {
     }
     /** @return void */
     public function next()
     {
     }
-    /** @return void */
+    /** @return mixed */
     public function key()
     {
     }

stubs/ext/spl/OuterIterator.php

@@ -2,6 +2,6 @@
 
 interface OuterIterator extends \Iterator
 {
-    /** @return Iterator */
+    /** @return Iterator|null */
     public function getInnerIterator();
 }