mozilla/extensions/interfaceinfo is an optional extension that implements:

- generic scriptable wrappers for interface infos
- dynamically populatable interface info set support
- a JS component that decompiles interface infos to idl

To build with gmake:
ac_add_options --enable-extensions=default,interfaceinfo

To build with nmake:
set MOZ_ENABLE_IIX=1

Note: the optional SOAP web service proxy (WSDl/Proxy) part of the xmlextras extension requires this extension.