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Fix chriskempson/tomorrow-theme#181.

Before:
![screenshot 2014-08-23 22 18 04](https://cloud.githubusercontent.com/assets/853977/4020679/2054975c-2ac8-11e4-9fbd-b04c8e7f820a.png)

After:
![screenshot 2014-08-23 22 49 19](https://cloud.githubusercontent.com/assets/853977/4020742/56dfb0be-2acc-11e4-9283-6ebec991ac92.png)