Fix unit tests

src/PhpSpreadsheet/Style/Style.php

@@ -82,7 +82,7 @@ class Style extends Supervisor
      */
     public function __construct($isSupervisor = false, $isConditional = false)
     {
-        parent::__construct($this->isSupervisor);
+        parent::__construct($isSupervisor);
 
         // Initialise values
         $this->conditionalStyles = [];

src/PhpSpreadsheet/Style/Supervisor.php

@@ -3,6 +3,7 @@
 namespace PhpOffice\PhpSpreadsheet\Style;
 
 use PhpOffice\PhpSpreadsheet\IComparable;
+use PhpOffice\PhpSpreadsheet\Worksheet\Worksheet;
 
 abstract class Supervisor implements IComparable
 {