Fix typo

Change-Id: I7e564eb1fb50c6db4cd904fd41b2540c054d4d4a
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/198767
Tested-by: Jenkins
Reviewed-by: Julien Nabet <serval2412@yahoo.fr>

sw/source/core/layout/flowfrm.cxx

@@ -1999,7 +1999,7 @@ bool SwFlowFrame::CheckMoveFwd( bool& rbMakePage, bool bKeep, bool bIgnoreMyOwnK
     {
         if (!pNxt)
             return true;
-        // We ignore non-null next, when it's empty master, than doesn't host a split fly:
+        // We ignore non-null next, when it's empty master, that doesn't host a split fly:
         if (pNxt->IsTextFrame())
         {
             auto pTextFrame = static_cast<const SwTextFrame*>(pNxt);