Remove unnecessary test.

Author: AndyDune

test/Helper/Placeholder/ContainerTest.php

@@ -439,12 +439,7 @@ public function testNoUsePrefixPostfixIfNoItems()
                         ->setPostfix("</h1>");
         $string = $this->container->toString();
         $this->assertEquals('', $string);
-    }
 
-    public function testUsePrefixPostfixIfEmptyItems()
-    {
-        $this->container->setPrefix("<h1>")
-            ->setPostfix("</h1>");
         $this->container->set('');
         $string = $this->container->toString();
         $this->assertEquals('<h1></h1>', $string);