Don't download SlimerJS and XULRunner in before_script; add build_tools to the list of directories to cache

.travis.yml

@@ -6,12 +6,6 @@ env:
 before_script:
   - "sh -e /etc/init.d/xvfb start"
   - npm install casperjs
-  - wget -P /tmp/j2me.js -N https://ftp.mozilla.org/pub/mozilla.org/labs/j2me.js/slimerjs-0.10.0pre-2014-12-17.zip
-  - unzip -d /tmp /tmp/j2me.js/slimerjs-0.10.0pre-2014-12-17.zip
-  - export PATH=$PATH:/tmp/slimerjs-0.10.0pre
-  - wget -P /tmp/j2me.js -N https://ftp.mozilla.org/pub/mozilla.org/xulrunner/releases/31.0/runtimes/xulrunner-31.0.en-US.linux-x86_64.tar.bz2
-  - tar x -C /tmp -f /tmp/j2me.js/xulrunner-31.0.en-US.linux-x86_64.tar.bz2
-  - export SLIMERJSLAUNCHER=/tmp/xulrunner/xulrunner
   - wget -P /tmp/j2me.js -N https://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/36.0b1-candidates/build1/jsshell-linux-x86_64.zip
   - unzip -d /tmp/js /tmp/j2me.js/jsshell-linux-x86_64.zip
   - export PATH=$PATH:/tmp/js
@@ -22,6 +16,7 @@ cache:
   directories:
     - node_modules
     - /tmp/j2me.js
+    - build_tools
 notifications:
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     channels: