Avoid redundant default values for properties

Author: oliverklee

src/CSSList/KeyFrame.php

@@ -12,12 +12,12 @@ class KeyFrame extends CSSList implements AtRule
     /**
      * @var string|null
      */
-    private $vendorKeyFrame = null;
+    private $vendorKeyFrame;
 
     /**
      * @var string|null
      */
-    private $animationName = null;
+    private $animationName;
 
     /**
      * @param string $vendorKeyFrame

src/OutputFormat.php

@@ -217,12 +217,12 @@ class OutputFormat
     /**
      * @var OutputFormatter|null
      */
-    private $oFormatter = null;
+    private $oFormatter;
 
     /**
      * @var OutputFormat|null
      */
-    private $oNextLevelFormat = null;
+    private $oNextLevelFormat;
 
     /**
      * @var int

src/Rule/Rule.php

@@ -29,7 +29,7 @@ class Rule implements Renderable, Commentable
     /**
      * @var RuleValueList|string|null
      */
-    private $mValue = null;
+    private $mValue;
 
     /**
      * @var bool