O problema está nas portas e continua dizendo que não pode ser feito:
make
===> License check disabled, port has not defined LICENSE
===> Found saved configuration for v8-3.10.4
===> Extracting for v8-3.10.4
=> SHA256 Checksum OK for v8-3.10.4.tar.xz.
===> Patching for v8-3.10.4
===> Applying FreeBSD patches for v8-3.10.4
===> v8-3.10.4 depends on file: /usr/local/bin/scons - found
===> v8-3.10.4 depends on shared library: execinfo.1 - found
===> Configuring for v8-3.10.4
===> Building for v8-3.10.4
scons: Reading SConscript files ...
scons: done reading SConscript files.
scons: Building targets ...
c++ -O2 -pipe -fno-strict-aliasing -o obj/release/accessors.o -c -fno-rtti -fno-exceptions -Wall -Werror -W -Wno-unused-parameter -Woverloaded-virtual -Wnon-virtual-dtor -m64 -O3 -fomit-frame-pointer -fdata-sections -ffunction-sections -ansi -DV8_TARGET_ARCH_X64 -DENABLE_DEBUGGER_SUPPORT -Isrc -I/usr/local/include -Isrc src/accessors.cc
c++ -O2 -pipe -fno-strict-aliasing -o obj/release/allocation.o -c -fno-rtti -fno-exceptions -Wall -Werror -W -Wno-unused-parameter -Woverloaded-virtual -Wnon-virtual-dtor -m64 -O3 -fomit-frame-pointer -fdata-sections -ffunction-sections -ansi -DV8_TARGET_ARCH_X64 -DENABLE_DEBUGGER_SUPPORT -Isrc -I/usr/local/include -Isrc src/allocation.cc
c++ -O2 -pipe -fno-strict-aliasing -o obj/release/api.o -c -fno-rtti -fno-exceptions -Wall -Werror -W -Wno-unused-parameter -Woverloaded-virtual -Wnon-virtual-dtor -m64 -O3 -fomit-frame-pointer -fdata-sections -ffunction-sections -ansi -DV8_TARGET_ARCH_X64 -DENABLE_DEBUGGER_SUPPORT -Isrc -I/usr/local/include -Isrc src/api.cc
virtual memory exhausted: Cannot allocate memory
scons: *** [obj/release/api.o] Error 1
scons: building terminated because of errors.
*** Error code 2
Stop in /usr/ports/lang/v8.
*** Error code 1
Stop in /usr/ports/lang/v8.
O VPS tem 256 MiB, o que é muito pequeno, mas pelo que eu pesquisei, as pessoas o rodam mesmo com uma quantidade menor de RAM.
Alguma dica?
Não tenho certeza se essa é a prática recomendada, mas você pode instalá-la assim:
curl -O ftp://ftp.freebsd.org/pub/FreeBSD/ports/packages/lang/v8-3.12.9.tbz && pkg_add -n v8-3.12.9.tbz
Percorra manualmente o ftp://ftp.freebsd.org/pub/FreeBSD/ports/packages/lang/ para verificar o nome do arquivo mais recente.
Existem métodos mais fáceis de instalar pacotes. Pesquise em ports/sysutils ou aguarde o pkgng no fBSD 9.1