First version of the presentation

Designed to run an estimated 20 minutes.

Covers:
* Why optimising reflows and repaints is worthwhile.
* How the browser renders a Web page.
* A selection of events that trigger a reflow or a repaint.
* A selection of techniques for optimising reflows and repaints.

This version of the talk will be given at OttawaJS on 12 February 2014.