GridPane column currently strictly respects the child's max width, never growing the column above the size. This is not necessary however, as the children can be aligned inside the area in case the area is bigger.
We should only strictly respect the column constraints max width when growing.

The same applies for rows/vgrow/max height.

---- previous description----
The GridPane inside the other GridPane's column is not stretched to fill the column when the parent GridPane's column has fillWidth = true.
This is a regression from JavaFX 2.2.40