Remove useless special handling of single-value ranges

... as they are treated by generic code just fine.
A check added to guard against overflow (0xFFFF + 1 -> 0).

Change-Id: Ibef85191eab82002981e12f83f313f3d122da74c
Reviewed-on: https://gerrit.libreoffice.org/50163Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>

sfx2/source/dialog/tabdlg.cxx

@@ -994,18 +994,6 @@ IMPL_LINK_NOARG(SfxTabDialog, BaseFmtHdl, Button*, void)
         {
             const sal_uInt16* pU = pTmpRanges + 1;
 
-            if ( *pTmpRanges == *pU )
-            {
-                // Range which two identical values -> only set one Item
-                sal_uInt16 nWh = pPool->GetWhich( *pTmpRanges );
-                m_pExampleSet->ClearItem( nWh );
-                aTmpSet.ClearItem( nWh );
-                // At the Outset of InvalidateItem,
-                // so that the change takes effect
-                m_pOutSet->InvalidateItem( nWh );
-            }
-            else
-            {
             // Correct Range with multiple values
             sal_uInt16 nTmp = *pTmpRanges, nTmpEnd = *pU;
             DBG_ASSERT( nTmp <= nTmpEnd, "Range is sorted the wrong way" );
@@ -1013,12 +1001,10 @@ IMPL_LINK_NOARG(SfxTabDialog, BaseFmtHdl, Button*, void)
             if ( nTmp > nTmpEnd )
             {
                 // If really sorted wrongly, then set new
-                    sal_uInt16 nTmp1 = nTmp;
-                    nTmp = nTmpEnd;
-                    nTmpEnd = nTmp1;
+                std::swap(nTmp, nTmpEnd);
             }
 
-                while ( nTmp <= nTmpEnd )
+            while ( nTmp && nTmp <= nTmpEnd ) // guard against overflow
             {
                 // Iterate over the Range and set the Items
                 sal_uInt16 nWh = pPool->GetWhich( nTmp );
@@ -1029,7 +1015,6 @@ IMPL_LINK_NOARG(SfxTabDialog, BaseFmtHdl, Button*, void)
                 m_pOutSet->InvalidateItem( nWh );
                 nTmp++;
             }
-            }
             // Go to the next pair
             pTmpRanges += 2;
         }