1. Install build dependencies

Python 2.7.X
Autoconf 2.13
Yasm 1.2.0 or newer
unzip
gconf2
gnum4
Perl
Gnu C Compiler version 4.9.3 or newer (9.X.X reccomended)
ccache (optional, see mozconfig)

2. Install runtime dependencies

libXt
zip
freetype
fontconfig
glibc
libffi
dbus
dbus-glib
gtk+2
alsa-lib
jack2 (optional, see mozconfig)
ffmpeg

3. prepare git submodule(s)

$ git submodule init && git submodule update


copy Mach build system example config into the root of webbrowser
as '.mozconfig'

$ cp doc/mozconfig.example .mozconfig

Optionally adjust .mozconfig to better suit your needs.

4. compile, test, and package Web Browser

./mach build

if this completes successfully you can test your build before packaging it

./mach run

if all is well package it

./mach package

and then install the resulting distrobution tarball on your system.
the tarball will be stored in the object directory/dist you set in .mozconfig