This was OString already; use it that way

Change-Id: Ia2268ce8a1e2111adb609c515e5bfa824afa66ce

sax/source/tools/fastserializer.cxx

@@ -225,7 +225,7 @@ namespace sax_fastparser {
     void FastSaxSerializer::writeFastAttributeList( const Reference< XFastAttributeList >& Attribs )
     {
 #ifdef DBG_UTIL
-        ::std::set<OUString> DebugAttributes;
+        ::std::set<OString> DebugAttributes;
 #endif
         Sequence< Attribute > aAttrSeq = Attribs->getUnknownAttributes();
         const Attribute *pAttr = aAttrSeq.getConstArray();
@@ -258,10 +258,9 @@ namespace sax_fastparser {
 
 #ifdef DBG_UTIL
             // Well-formedness constraint: Unique Att Spec
-            OUString const name(OStringToOUString(getId(nToken),
-                                                  RTL_TEXTENCODING_UTF8));
-            assert(DebugAttributes.find(name) == DebugAttributes.end());
-            DebugAttributes.insert(name);
+            OString const nameId(getId(nToken));
+            assert(DebugAttributes.find(nameId) == DebugAttributes.end());
+            DebugAttributes.insert(nameId);
 #endif
 
             writeBytes(toUnoSequence(maEqualSignAndQuote));