fix pdf print bug in chrome 33 https://github.com/hakimel/reveal.js/commit/08fb6cb2f96a6d97aaa21c35a925ebb59b0b0070#diff-eacf331f0ffc35d4b482f1d15a887d3b
Merge pull request #40 from jonanh/master

fix pdf print bug in chrome 33