Dry layout support for RenderBox

Summary

Context

Description of change

Migration guide

Timeline

References

Summary

Context

RenderBox.computeMinIntrinsicWidth and friends).

Description of change

Subclasses of RenderBox need to override the new computeDryLayout method
if they are used as a descendant of a RenderObject that may query the intrinsic
size of its children. Examples of widgets that do this are IntrinsicHeight
and IntrinsicWidth.

The default implementation of RenderBox.performResize also uses the size
computed by computeDryLayout to perform the resize. Overriding performResize
is therefore no longer necessary.

Migration guide