related tdf#38778 Speed-up: Do not traverse the whole array

It is known that text attributes are sorted inside SwpHints.
No need to check all entries if special position is provided.

Change-Id: Iac92cd40cd6d094d158f3b50fd768f47029ccdce
Reviewed-on: https://gerrit.libreoffice.org/43911Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

sw/source/filter/ww8/wrtw8nds.cxx

@@ -663,10 +663,16 @@ bool SwWW8AttrIter::IsTextAttr( sal_Int32 nSwPos )
         for (size_t i = 0; i < pTextAttrs->Count(); ++i)
         {
             const SwTextAttr* pHt = pTextAttrs->Get(i);
-            if ( ( pHt->HasDummyChar() || pHt->HasContent() )
-                 && (pHt->GetStart() == nSwPos) )
+            if (nSwPos == pHt->GetStart())
             {
-                return true;
+                if (pHt->HasDummyChar() || pHt->HasContent() )
+                {
+                    return true;
+                }
+            }
+            else if (nSwPos < pHt->GetStart())
+            {
+                break; // sorted by start
             }
         }
     }