🐛 Using NavigationView without AppBar breaks content

[NicolaVerbeeck]

Describe the bug
If you use a NavigationView (with a NavigationPane in compact mode) with for example a NavgationBody content AND you do not supply the AppBar, the width of the content is set to 0.

To Reproduce
Steps to reproduce the behavior:

NavigationView(
              key: _navKey,
              pane: NavigationPane(
                selected: ...,
                onChanged: ...,
                displayMode: PaneDisplayMode.compact,
                items: ...,
              ),
              content: NavigationBody(...),
)

Expected behavior
Content should fill as with the appbar case

I could fix it by changing the line 166 in view.dart to:
return LayoutBuilder(builder: (context, constraints) => SizedBox(width: constraints.maxWidth, height: 0));
This ensures the stack will get its width from somewhere (all the other children are using positioned in this case).