putting back file permissions change, but with default io flags.

modules/libpref/src/nsPrefService.cpp

@@ -480,7 +480,9 @@ nsresult nsPrefService::WritePrefFile(nsIFile* aFile)
 
   // execute a "safe" save by saving through a tempfile
   rv = NS_NewSafeLocalFileOutputStream(getter_AddRefs(outStreamSink),
-                                       aFile);
+                                       aFile,
+                                       -1,
+                                       0600);
   if (NS_FAILED(rv)) 
       return rv;
   rv = NS_NewBufferedOutputStream(getter_AddRefs(outStream), outStreamSink, 4096);