External Libraries: Backport upstream PHP 8.5 fixes for SimplePie.

After the update to v1.9.0 in [60771], this merges a single bug fix, in absence of a new upstream release in time for 6.9 Beta.

References:

* [simplepie/simplepie#949 Original upstream PR]

Props swissspidy.
Fixes #63961.

git-svn-id: https://develop.svn.wordpress.org/trunk@60947 602fd350-edb4-49c9-b593-d223f7449a82

Author: swissspidy

src/wp-includes/SimplePie/src/IRI.php

@@ -170,7 +170,7 @@ public function __get(string $name)
             $return = null;
         }
 
-        if ($return === null && isset($this->normalization[$this->scheme][$name])) {
+        if ($return === null && isset($this->scheme, $this->normalization[$this->scheme][$name])) {
             return $this->normalization[$this->scheme][$name];
         }
 
@@ -623,6 +623,10 @@ protected function remove_iunreserved_percent_encoded(array $match)
      */
     protected function scheme_normalization()
     {
+        if ($this->scheme === null) {
+            return;
+        }
+
         if (isset($this->normalization[$this->scheme]['iuserinfo']) && $this->iuserinfo === $this->normalization[$this->scheme]['iuserinfo']) {
             $this->iuserinfo = null;
         }