[Config] Only using filemtime to check file freshness

Author: dmifedorenko

src/Symfony/Component/Config/Resource/FileResource.php

@@ -60,7 +60,7 @@ public function getResource()
      */
     public function isFresh($timestamp)
     {
-        return file_exists($this->resource) && @filemtime($this->resource) <= $timestamp;
+        return false !== ($filemtime = @filemtime($this->resource)) && $filemtime <= $timestamp;
     }
 
     public function serialize()

src/Symfony/Component/Config/Resource/ReflectionClassResource.php

@@ -37,11 +37,11 @@ public function isFresh($timestamp)
         }
 
         foreach ($this->files as $file => $v) {
-            if (!file_exists($file)) {
+            if (false === $filemtime = @filemtime($file)) {
                 return false;
             }
 
-            if (@filemtime($file) > $timestamp) {
+            if ($filemtime > $timestamp) {
                 return $this->hash === $this->computeHash();
             }
         }