(formatting) Change Tab Size to 2 spaces and correct indentation

The formatting of the imgLoad Function was incorrect of the MDN documentation page. I fixed the tab spacing and corrected the number of tabs on line 48. No source code was altered and the original functionality remains untouched.
Before:
![screen shot 2014-10-02 at 4 30 02 pm](https://cloud.githubusercontent.com/assets/4704965/4500142/713c1daa-4a8c-11e4-952a-ae2fb0aa4e78.png)
After:
![screen shot 2014-10-02 at 4 32 35 pm](https://cloud.githubusercontent.com/assets/4704965/4500144/71530394-4a8c-11e4-9569-3dc6f69ceb07.png)