IE8 Javascript compatibility

Due to some JS calls incompatible with IE8 relating to the sometimes-present fixed left hand side menu, a JS error prevented IE8 users from viewing more important content, notably the body of the Downloads page.

Screenshot before

![ie8-before](https://cloud.githubusercontent.com/assets/20520/4347844/bebfe566-416d-11e4-8e0a-ff236bd27ede.png)

Screenshot after

![ie8-after](https://cloud.githubusercontent.com/assets/20520/4347845/bec66ce2-416d-11e4-9d2c-529e871344f2.png)