Content Search: expanding the row header column

This is for Chrome. This makes the comparison grid 2 pixels wider but the width of their container div remains the same (at 1152px).

**Before**
![image](https://f.cloud.github.com/assets/86290/812211/20557866-eeec-11e2-8ec2-f9b1180107f3.png)

**After**
![image](https://f.cloud.github.com/assets/86290/812205/0dee71be-eeec-11e2-918c-5e95d90a2dc7.png)