Dependency error about jsdetox HOT 5 CLOSED

$ gem uninstall libv8
$ gem install therubyracer

Fetching gem metadata from https://rubygems.org/...........
Fetching version metadata from https://rubygems.org/...
Fetching dependency metadata from https://rubygems.org/..
Resolving dependencies......
Using rake 10.5.0
Using i18n 0.7.0
Using multi_json 1.11.2
Using bundler 1.11.2
Using haml 3.1.8
Using hexdump 0.2.3
Using rack 1.6.4
Using json 1.8.3
Installing libv8 3.3.10.4
Using mime-types 1.25.1
Using polyglot 0.3.5
Using mini_portile2 2.0.0
Using tilt 1.3.7
Using thor 0.15.4
Using sass 3.4.21
Using activesupport 3.2.22.1
Using url_mount 0.2.1
Using rack-protection 1.5.3
Installing therubyracer 0.9.8 with native extensions

Gem::Ext::BuildError: ERROR: Failed to build gem native extension.

    /usr/bin/ruby2.1 extconf.rb
*** extconf.rb failed ***
Could not create Makefile due to some reason, probably lack of necessary
libraries and/or headers.  Check the mkmf.log file for more details.  You may
need configuration options.

Provided configuration options:
    --with-opt-dir
    --without-opt-dir
    --with-opt-include
    --without-opt-include=${opt-dir}/include
    --with-opt-lib
    --without-opt-lib=${opt-dir}/lib
    --with-make-prog
    --without-make-prog
    --srcdir=.
    --curdir
    --ruby=/usr/bin/ruby2.1
extconf.rb:15:in `<main>': undefined method `include_path' for Libv8:Module (NoMethodError)

extconf failed, exit code 1

Gem files will remain installed in /var/lib/gems/2.1.0/gems/therubyracer-0.9.8 for inspection.
Results logged to /var/lib/gems/2.1.0/extensions/x86_64-linux/2.1.0/therubyracer-0.9.8/gem_make.out
Using treetop 1.4.15
Using nokogiri 1.6.7.2
Using http_router 0.10.2
Using sinatra 1.3.6
An error occurred while installing therubyracer (0.9.8), and Bundler cannot continue.
Make sure that `gem install therubyracer -v '0.9.8'` succeeds before bundling.

./jsdetox
[JSDetox] Loading framework ... Could not find gem 'therubyracer (= 0.9.8) ruby' in the gems available on this machine.
Run `bundle install` to install missing gems.