incorrect bbox of text 

With current master, frames around  texts are incorrectly located.

Here is some test output.

In v1.2.x branch, the results are correct.

![text_bbox_test_v1 2](https://f.cloud.github.com/assets/95962/572594/82cb33e8-c79e-11e2-8a9c-68945a2e69d4.png)

The frames are shifted in the master branch. Note that they have too much room toward the top of the texts.

![text_bbox_test_master](https://f.cloud.github.com/assets/95962/572598/a737b9c2-c79e-11e2-853d-06b1f52e6be8.png)

These outputs are created with usetex=False. With usetex=True, the results are still incorrect, but the shifted direction of frames are different.

I am labeling this as a v1.3.x blocker, but change as you wish.