Text overflow calculation not correct

[michielvandergeest]

It seems the calculation of when to apply text overflow (i.e. adding ellipsis) is slightly off.

See the following Blits playground example:https://playground.lightningjs.io/#4VfPB4vxpOLU

The text technically fits inside of the 270px max width, but still get's cut off. If the max width is increased with 2 pixels, the text is not truncated, and the reported text width is still below 270