Fix: Half-Pixel blur due to non-integer values

`font.lineHeight` returns non-integer value, which causes the second line of TIToken to be blur. This PR fixes this.
![screen shot 2014-01-31 at 4 19 42 pm](https://f.cloud.github.com/assets/955238/2056272/bd82c644-8ad6-11e3-8b44-42235794b550.png)