minor symfony#24741 [HttpFoundation] refactoring: calculate when need (ReenExe)

This PR was submitted for the 2.7 branch but it was merged into the 3.4 branch instead (closes symfony#24741).

Discussion
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[HttpFoundation] refactoring: calculate when need

| Q             | A
| ------------- | ---
| Branch?       | no
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | no
| License       | MIT
| Doc PR        | no

HttpFoundation Request optimize

Commits
-------

79e8f57 [HttpFoundation] refactoring: calculate when need

Author: fabpot

src/Symfony/Component/HttpFoundation/Request.php

@@ -1928,12 +1928,12 @@ protected function prepareBaseUrl()
      */
     protected function prepareBasePath()
     {
-        $filename = basename($this->server->get('SCRIPT_FILENAME'));
         $baseUrl = $this->getBaseUrl();
         if (empty($baseUrl)) {
             return '';
         }
 
+        $filename = basename($this->server->get('SCRIPT_FILENAME'));
         if (basename($baseUrl) === $filename) {
             $basePath = dirname($baseUrl);
         } else {
@@ -1954,8 +1954,6 @@ protected function prepareBasePath()
      */
     protected function preparePathInfo()
     {
-        $baseUrl = $this->getBaseUrl();
-
         if (null === ($requestUri = $this->getRequestUri())) {
             return '/';
         }
@@ -1968,12 +1966,14 @@ protected function preparePathInfo()
             $requestUri = '/'.$requestUri;
         }
 
+        if (null === ($baseUrl = $this->getBaseUrl())) {
+            return $requestUri;
+        }
+
         $pathInfo = substr($requestUri, strlen($baseUrl));
-        if (null !== $baseUrl && (false === $pathInfo || '' === $pathInfo)) {
+        if (false === $pathInfo || '' === $pathInfo) {
             // If substr() returns false then PATH_INFO is set to an empty string
             return '/';
-        } elseif (null === $baseUrl) {
-            return $requestUri;
         }
 
         return (string) $pathInfo;