Fixed form inline button overlap in Safari (#8795)

Before:

![image](https://f.cloud.github.com/assets/56288/874065/b4cb1540-f884-11e2-9e03-a0081194e48e.png)

After:

![image](https://f.cloud.github.com/assets/56288/874052/91604c7e-f884-11e2-864d-91c5e976b5a2.png)