This makes selenium in Firefox work on the Mac.

serializer/cross/serializer.cc

Index: serializer/cross/serializer.cc
===================================================================
--- serializer/cross/serializer.cc	(revision 25628)
+++ serializer/cross/serializer.cc	(working copy)
@@ -324,10 +324,10 @@
       writer_->BeginCompacting();
       writer_->OpenArray();
       const Skin::InfluencesArray& influences_array = skin->influences();
-      for (int i = 0; i != influences_array.size(); ++i) {
+      for (Skin::InfluencesArray::size_type i = 0; i != influences_array.size(); ++i) {
         const Skin::Influences& influences = influences_array[i];
         writer_->OpenArray();
-        for (int j = 0; j != influences.size(); ++j) {
+        for (Skin::Influences::size_type j = 0; j != influences.size(); ++j) {
           const Skin::Influence& influence = influences[j];
           Serialize(writer_, influence.matrix_index);
           Serialize(writer_, influence.weight);