Clipped characters for large fonts with right bearing when using the raster engine on Mac OS X

To reproduce:

1. Start the text edit demo and select all text
2. Set the font to Lucida Grande
3. Set the size of the text to 48
4. Set the font style to italic

You should see that characters such as l, i and n are clipped on the right edge. This is most likely because the bearing is not included in the bounding rect returned by the font engine, which is used to calculate the size needed for the glyphs in the texture glyph cache. For small fonts the default padding in the cache will be sufficient to hide the error, but for large fonts the bearing becomes to large and the glyphs are clipped.