This automates the steps for compiling a 32bits Firefox on a 64bits Ubuntu machine.
To debug Firefox with http://rr-project.org/.
Read the top of the script
./fx-32-on-64.sh, maybe tweak a couple variables,
and then run it.
This uses a chroot, because these days, getting all the 32bits packages to compile a Firefox 32 on Ubuntu 64 is not trivial.