fixed tooltip hover on unsocial send buttons

In response to https://trello.com/c/8MW3soSa/184-tooltips-for-send-this-in-share-bar-are-still-borkred

![screenshot 2014-06-18 16 38 43](https://cloud.githubusercontent.com/assets/1597375/3320935/2189f236-f731-11e3-9a05-a84f3d1ce573.png)
Yeah. But wouldn't the left position need to be set still? It's not auto-centered, it's left-aligned to the border of the container.

![screenshot 2014-06-19 09 08 55](https://cloud.githubusercontent.com/assets/1597375/3328316/55e93bd8-f7bb-11e3-8cb2-c06a0251b02c.png)