jscored.lib exports typeinfo and vtable symbols when it shouldn't

There are over a hundred new exports in qtwebkit, that are being triggered by the linking against the static library jscored.lib. The reason these symbols are being exported is because this line "MMP_RULES += $$MMP_RULES_DONT_EXPORT_ALL_CLASS_IMPEDIMENTA" in symbian-mmp.conf is not resulting in "OPTION_REPLACE ARMCC --export_all_vtbl // don't use --export_all_vtbl" being inserted in the MMP file.

Adding extra keywords to that line results in them being present in the MMP file, so there's something about that construct that's causing the problem. However, the same construct works fine to insert that line into qtwebkit's MMP file. Something about jscored being a static library?