Diff for new files should be all green.

When saving a new file, the diff should be all green (only added text).  The diff looks weird when it shows the sample text.

![before](https://f.cloud.github.com/assets/11674/141336/2c0d4928-7245-11e2-85ca-4da67a63edc5.png)

All green is much better.  \o/

![after](https://f.cloud.github.com/assets/11674/141344/85db3cc6-7245-11e2-9ad6-2378605c25c7.png)