MAGETWO-52923: Switching to Varnish causes category menu to force HTTPS links

- add getHttpHost to mock in unit test

Author: bwaters

lib/internal/Magento/Framework/App/Test/Unit/Config/ScopePoolTest.php

@@ -68,7 +68,8 @@ protected function setUp()
                     'setParams',
                     'getCookie',
                     'isSecure',
-                    'getServer'
+                    'getServer',
+                    'getHttpHost'
                 ]
             )->getMock();
         $reflection = new \ReflectionClass(get_class($this->_object));