$ uname -rms
Linux 4.1.12-gentoo x86_64

$ firefox -v
Mozilla Firefox 42.0

[ebuild R ] www-plugins/adobe-flash-11.2.202.554::gentoo USE="(-debug) -kde (-selinux)" ABI_X86="32 64 (-x32)" CPU_FLAGS_X86="sse2" 0 KiB

serv0 ~ # emerge -auvDN world

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild U ~] media-libs/libpng-1.6.20:0/16::gentoo [1.6.19:0/16::gentoo] USE="apng (-neon) -static-libs" ABI_X86="32 (64) (-x32)" 931 KiB
[ebuild U ] x11-proto/xproto-7.0.28::gentoo [7.0.27::gentoo] USE="-doc" ABI_X86="32 (64) (-x32)" 294 KiB
[ebuild U ] x11-proto/kbproto-1.0.7::gentoo [1.0.6-r1::gentoo] ABI_X86="32 (64) (-x32)" 245 KiB
[ebuild U ~] dev-libs/nspr-4.11::gentoo [4.10.10-r1::gentoo] USE="-debug" ABI_X86="32 (64) (-x32)" 1 108 KiB
[ebuild U ] media-fonts/font-util-1.3.1::gentoo [1.3.0::gentoo] 150 KiB
[ebuild U ] x11-proto/randrproto-1.5.0::gentoo [1.4.0-r1::gentoo] ABI_X86="32 (64) (-x32)" 139 KiB
[ebuild U ] x11-libs/libdrm-2.4.65::gentoo [2.4.59::gentoo] USE="libkms -static-libs -valgrind%" ABI_X86="32 (64) (-x32)" VIDEO_CARDS="-amdgpu% (-exynos) (-freedreno) -intel -nouveau (-omap) -radeon (-tegra) -vmware" 631 KiB
[ebuild U ] x11-libs/libpciaccess-0.13.4::gentoo [0.13.3::gentoo] USE="zlib -static-libs" ABI_X86="32 (64) (-x32)" 364 KiB
[ebuild U ] x11-libs/libXdmcp-1.1.2::gentoo [1.1.1-r1::gentoo] USE="-doc -static-libs" ABI_X86="32 (64) (-x32)" 324 KiB
[ebuild U ] x11-libs/libfontenc-1.1.3::gentoo [1.1.2::gentoo] USE="-static-libs" 295 KiB
[ebuild U ] media-fonts/font-alias-1.0.3-r1::gentoo [1.0.3::gentoo] 0 KiB
[ebuild U ] x11-apps/xlsatoms-1.1.2::gentoo [1.1.1::gentoo] 121 KiB
[ebuild U ] x11-base/xorg-drivers-1.17::gentoo [1.16::gentoo] INPUT_DEVICES="keyboard mouse -acecad -aiptek -elographics -evdev -fpit -hyperpen -joystick (-libinput) -mutouch -penmount -synaptics -tslib -vmmouse -void -wacom" VIDEO_CARDS="nvidia -amdgpu% -apm -ast -chips -cirrus -dummy -epson -fbdev -fglrx (-freedreno) (-geode) -glint -i128 (-i740) -intel -mach64 -mga -neomagic -nouveau -nv (-omap) (-omapfb) -qxl -r128 -radeon -radeonsi -rendition -s3 -s3virge -savage -siliconmotion -sisusb (-sunbw2) (-suncg14) (-suncg3) (-suncg6) (-sunffb) (-sunleo) (-suntcx) -tdfx (-tegra) -tga -trident -tseng -vesa -via -virtualbox -vmware (-voodoo) (-modesetting%) (-v4l%)" 0 KiB
[ebuild N ] app-misc/c_rehash-1.7-r1::gentoo 0 KiB
[ebuild U ] dev-libs/openssl-1.0.2e::gentoo [1.0.2d::gentoo] USE="asm tls-heartbeat zlib -bindist -gmp -kerberos -rfc3779 -sctp -static-libs {-test} -vanilla" ABI_X86="32 (64) (-x32)" CPU_FLAGS_X86="(sse2)" 5 134 KiB
[blocks b ] [ebuild U ] x11-libs/xcb-util-cursor-0.1.2::gentoo [0.1.1-r1::gentoo] USE="-doc -static-libs {-test}" ABI_X86="32 (64) (-x32)" 283 KiB
[ebuild U ] x11-libs/libxcb-1.11.1:0/1.11.1::gentoo [1.11-r1:0/1.11::gentoo] USE="xkb -doc (-selinux) -static-libs {-test}" ABI_X86="32 (64) (-x32)" 508 KiB
[ebuild U ] sys-apps/portage-2.2.24::gentoo [2.2.20.1::gentoo] USE="(ipc) xattr -build -doc -epydoc (-selinux)" LINGUAS="ru" PYTHON_TARGETS="python2_7 python3_4 (-pypy) -python3_3 (-python3_5)" 950 KiB
[ebuild U ] x11-libs/libX11-1.6.3::gentoo [1.6.2::gentoo] USE="-doc -ipv6 -static-libs {-test}" ABI_X86="32 (64) (-x32)" 2 309 KiB
[ebuild U ] x11-libs/libXrender-0.9.9::gentoo [0.9.8::gentoo] USE="-static-libs" ABI_X86="32 (64) (-x32)" 300 KiB
[ebuild U ] x11-libs/libxkbfile-1.0.9::gentoo [1.0.8::gentoo] USE="-static-libs" 340 KiB
[ebuild U ] x11-apps/xmodmap-1.0.9::gentoo [1.0.8::gentoo] 140 KiB
[ebuild U ] x11-apps/xcmsdb-1.0.5::gentoo [1.0.4::gentoo] 143 KiB
[ebuild U ] x11-libs/libXi-1.7.5::gentoo [1.7.4::gentoo] USE="-doc -static-libs" ABI_X86="32 (64) (-x32)" 454 KiB
[ebuild U ] x11-libs/libXrandr-1.5.0::gentoo [1.4.2::gentoo] USE="-static-libs" ABI_X86="32 (64) (-x32)" 308 KiB
[ebuild U ] x11-libs/libXvMC-1.0.9::gentoo [1.0.8::gentoo] USE="-static-libs" ABI_X86="32 (64) (-x32)" 306 KiB
[ebuild U ] x11-apps/xvinfo-1.1.3::gentoo [1.1.2::gentoo] 121 KiB
[ebuild U ] x11-apps/xgamma-1.0.6::gentoo [1.0.5::gentoo] 121 KiB
[ebuild U ] x11-apps/xkbevd-1.1.4::gentoo [1.1.3::gentoo] 149 KiB
[ebuild U ] x11-misc/xkeyboard-config-2.16::gentoo [2.14::gentoo] 946 KiB
[ebuild U ] x11-apps/xev-1.2.2::gentoo [1.2.1::gentoo] 130 KiB
[ebuild U ] x11-apps/xinput-1.6.2::gentoo [1.6.1::gentoo] 155 KiB
[ebuild U ] x11-apps/xdpyinfo-1.3.2::gentoo [1.3.1::gentoo] USE="-dga -dmx -xinerama" 139 KiB
[ebuild U ] x11-apps/setxkbmap-1.3.1::gentoo [1.3.0::gentoo] 131 KiB
[ebuild U ] dev-python/certifi-2015.11.20::gentoo [2015.9.6.2::gentoo] PYTHON_TARGETS="python2_7 python3_4 (-pypy) (-pypy3) -python3_3 (-python3_5)" 356 KiB
[ebuild U ] x11-libs/libXt-1.1.5::gentoo [1.1.4::gentoo] USE="-static-libs" ABI_X86="32 (64) (-x32)" 754 KiB
[ebuild U ] x11-apps/xauth-1.0.9-r2::gentoo [1.0.9-r1::gentoo] USE="-ipv6" 0 KiB
[ebuild U ] x11-apps/x11perf-1.6.0::gentoo [1.5.4::gentoo] 187 KiB
[ebuild U ] x11-apps/xhost-1.0.7::gentoo [1.0.6::gentoo] USE="-ipv6" 133 KiB
[ebuild U ] x11-apps/smproxy-1.0.6::gentoo [1.0.5::gentoo] 129 KiB
[ebuild U ] x11-libs/libXaw-1.0.13::gentoo [1.0.12::gentoo] USE="-deprecated -doc -static-libs" ABI_X86="32 (64) (-x32)" 659 KiB
[ebuild U ] x11-apps/xinit-1.3.4-r1::gentoo [1.3.3-r1::gentoo] USE="minimal -systemd%" 162 KiB
[ebuild NS ] dev-lang/php-5.6.14:5.6::gentoo [5.4.45:5.4::gentoo] USE="bcmath berkdb bzip2 cli crypt ctype curl fileinfo filter fpm gdbm hash iconv json mysql mysqli nls opcache pdo phar posix readline session simplexml sockets ssl sysvipc tokenizer unicode xml xmlreader xmlwriter zip zlib -apache2 -calendar -cdb -cgi -cjk -debug -embed -enchant -exif (-firebird) -flatfile (-frontbase) -ftp -gd -gmp -imap -inifile -intl -iodbc -ipv6 -kerberos -ldap -ldap-sasl -libedit -libmysqlclient -mhash -mssql -oci8-instant-client -odbc -pcntl -postgres -qdbm -recode (-selinux) -sharedmem -snmp -soap -spell -sqlite -sybase-ct -systemd -threads -tidy -truetype -vpx -wddx -xmlrpc -xpm -xslt" 13 745 KiB
[ebuild NS ] virtual/httpd-php-5.6:5.6::gentoo [5.4-r1:5.4::gentoo] 0 KiB
[ebuild U ] app-eselect/eselect-opengl-1.3.1-r4::gentoo [1.2.7::gentoo] 3 KiB
[ebuild U ] media-libs/mesa-11.0.6::gentoo [10.3.7-r1::gentoo] USE="classic dri3 egl gallium gbm llvm nptl udev xvmc -bindist -d3d9% -debug -gles1 -gles2 -opencl -openmax -osmesa -pax_kernel -pic (-selinux) -vaapi% -vdpau -wayland -xa (-openvg%)" ABI_X86="32 (64) (-x32)" VIDEO_CARDS="(-freedreno) -i915 -i965 -ilo -intel -nouveau -r100 -r200 -r300 -r600 -radeon -radeonsi -vmware" 7 103 KiB
[ebuild UD ] x11-base/xorg-server-1.16.4-r5:0/1.16.1::gentoo [1.17.4:0/1.17.4::gentoo] USE="nptl suid udev xorg -dmx -doc -glamor -ipv6 -kdrive -minimal (-selinux) -static-libs -systemd -tslib -unwind -wayland -xnest -xvfb (-libressl%) (-xephyr%)" 0 KiB
[ebuild U ] media-libs/libepoxy-1.3.1::gentoo [1.2::gentoo] USE="{-test}" ABI_X86="32 (64) (-x32)" 278 KiB
[ebuild U ] x11-drivers/xf86-input-keyboard-1.8.1::gentoo [1.8.0::gentoo] 312 KiB
[ebuild U ] x11-apps/xdriinfo-1.0.5::gentoo [1.0.4::gentoo] 119 KiB
[ebuild UD ] x11-drivers/nvidia-drivers-340.93-r1:0/340::gentoo [340.96:0/340::gentoo] USE="X multilib tools -acpi -pax_kernel -uvm" 0 KiB