app-arch/unzip app-arch/zip sys-devel/binutils from RDEPENDS are only needed in build time.
dev-libs/expat dev-libs/libIDL x11-libs/libXmu from RDEPENDS too are completely unneded, because it doesn't link with it:
$ readelf -d /usr/lib64/firefox/libxpcom.so /usr/lib64/firefox/mozilla-xremote-client /usr/lib64/firefox/plugin-container /usr/lib64/firefox/firefox-bin /usr/lib64/firefox/libxul.so /usr/lib64/firefox/crashreporter /usr/lib64/firefox/libmozalloc.so /usr/lib64/firefox/components/libmozgnome.so /usr/lib64/firefox/components/libbrowsercomps.so /usr/lib64/firefox/firefox |grep -E 'expat|IDL|Xmu'
and doesn't even load it in rintime:
$ grep -E 'expat|IDL|Xmu' /proc/$(pgrep firefox)/maps
Created attachment 319044 [details]
emerge --info output
For even more proof, just look at iceweasel build rules from debian.
Created attachment 319052 [details]
You can check against what is posted, well you are correct on a few you are also incorrect on a few, I could care less about debian and icewease, they provide binaries not source builds.
Created attachment 319072 [details]
Well, you are talking about /usr/lib64/libexpat.so.1.6.0 which is loaded in your case. It's not direct firefox dep, It's here just because default fontconfig in gentoo links with it (but it can with libxml2 too, which firefox is using). Here's use's of my build, be on the safe side:
www-client/firefox-14.0.1 was built with the following:
USE="alsa ipc jit minimal system-sqlite webm -bindist -custom-cflags -custom-optimization -dbus -debug -gstreamer -libnotify -pgo (-selinux) -startup-notification -wifi" LINGUAS="-af -ak -ar -as -ast -be -bg -bn_BD -bn_IN -br -bs -ca -cs -csb -cy -da -de -el -en_GB -en_ZA -eo -es_AR -es_CL -es_ES -es_MX -et -eu -fa -fi -fr -fy_NL -ga_IE -gd -gl -gu_IN -he -hi_IN -hr -hu -hy_AM -id -is -it -ja -kk -km -kn -ko -ku -lg -lt -lv -mai -mk -ml -mr -nb_NO -nl -nn_NO -nso -or -pa_IN -pl -pt_BR -pt_PT -rm -ro -ru -si -sk -sl -son -sq -sr -sv_SE -ta -ta_LK -te -th -tr -uk -vi -zh_CN -zh_TW -zu"
and my /proc/maps attached.
>I could care less about debian and icewease, they provide binaries not source builds
Actually, you can re-build every package with apt-build.
If you find anything in newer builds please let us know.