More idiomatic use of constraints in performResize.
Trivial fixes to comments.
Make ProxyBox not use BoxParentData since it ignores the field.
Make applyPaintTransform more helpful if you use a different ParentData
subclass than RenderBox expects.
Make debugAssertIsValid actually fulfill its contract in RenderObject as
documented.
Add a childBefore for symmetry (we already had childAfter).
Fix the way we dump the child list when there's no children in a
multichild render object.
More asserts in the rendering test library.
15fb5c4ca6