anchor.diff:  FROM ruby:2.3.0-slim
   
  -ENV PHANTOM_JS_TAG 2.0.0
  +ENV NODE_VERSION 0.12.10
  +
  +# gpg keys listed at https://github.com/nodejs/node
  +RUN set -ex \
  +  && for key in \
  +    9554F04D7259F04124DE6B476D5A82AC7E37093B \
  +    94AE36675C464D64BAFA68DD7434390BDBE9B9C5 \
  +    0034A06D9D9B0064CE8ADF6BF1747F4AD2306D93 \
  +    FD3A5288F042B6850C66B31F09FE44734EB7990E \
  +    71DCFD284A79C3B38668286BC97EC7A07EDE3FC1 \
  +    DD8F2338BAE7501E3DD5AC78C273792F7D83545D \
  +    B9AE9905FFD7803F25714661B63B535A4C206CA9 \
  +    C4F0DFFF4E8C1A8236409D08E73BC641CC11F4C8 \
  +  ; do \
  +    gpg --keyserver ha.pool.sks-keyservers.net --recv-keys "$key"; \
  +  done
  +
  +RUN buildDeps='curl ca-certificates xz-utils' \
  +        && set -x \
  +        && apt-get update && apt-get install -y $buildDeps --no-install-recommends \
  +        && rm -rf /var/lib/apt/lists/* \
  +        && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/node-v$NODE_VERSION-linux-x64.tar.xz" \
  +        && curl -SLO "https://nodejs.org/dist/v$NODE_VERSION/SHASUMS256.txt.asc" \
  +        && gpg --verify SHASUMS256.txt.asc \
  +        && grep " node-v$NODE_VERSION-linux-x64.tar.xz\$" SHASUMS256.txt.asc | sha256sum -c - \
  +        && tar -xJf "node-v$NODE_VERSION-linux-x64.tar.xz" -C /usr/local --strip-components=1 \
  +        && rm "node-v$NODE_VERSION-linux-x64.tar.xz" SHASUMS256.txt.asc \
  +        && apt-get purge -y --auto-remove $buildDeps
   
   RUN apt-get update -qq && apt-get upgrade -y && apt-get install -y \
       git \
  +    wget \
       build-essential \
       g++ \
       flex \
  
positive.code:     gperf \
      perl \
      libsqlite3-dev \
      libfontconfig1-dev \
      libicu-dev \
      libfreetype6 \
      libssl-dev \
      libpng-dev \
      libjpeg-dev \
      libqt5webkit5-dev
  
  # for image manipulation
  RUN apt-get install -y imagemagick
  
negative.code: # for capybara-webkit
  RUN apt-get install -y libqt4-webkit libqt4-dev xvfb
  
  # phantomjs
  RUN npm install -g phantomjs-prebuilt
  
  ENV APP_HOME /myapp
  RUN mkdir $APP_HOME
  