Fix typo

Change-Id: I907b28c98133162a31835ebaeae6244dc8735752
Reviewed-on: https://gerrit.libreoffice.org/70106
Tested-by: Jenkins
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>

UnoControls/source/controls/progressbar.cxx

@@ -67,13 +67,13 @@ Any SAL_CALL ProgressBar::queryInterface( const Type& rType )
     Reference< XInterface > xDel = BaseControl::impl_getDelegator();
     if ( xDel.is() )
     {
-        // If an delegator exist, forward question to his queryInterface.
-        // Delegator will ask his own queryAggregation!
+        // If a delegator exists, forward question to its queryInterface.
+        // Delegator will ask its own queryAggregation!
         aReturn = xDel->queryInterface( rType );
     }
     else
     {
-        // If an delegator unknown, forward question to own queryAggregation.
+        // If a delegator is unknown, forward question to own queryAggregation.
         aReturn = queryAggregation( rType );
     }