computeDistanceToActualBaseline method
Even though the text is rotated, it is still useful to have a baseline along which to layout objects. (For example in the MongolInputDecorator.)
Valid only after layout has been called.
Implementation
double computeDistanceToActualBaseline(TextBaseline baseline) {
assert(_debugAssertTextLayoutIsValid);
return _layoutCache!.layout.getDistanceToBaseline(baseline);
}