Typesettable is an abstract class, representing something that can be typeset.
width: number, height: numberDefault: 0
The width and height properties should be set by the typeset() method, and report the node size.
context: ContextThe Typesettable node’s typesetting context, which defines things like the base font size or line height.
typeset()When this method is called, the Typesettable node should perform any layout tasks and end up with a width and height.