Directional focus edge traversal behavior. (#161285)
Fixes: #160843
This PR adds edge behavior feature for traversing focus using arrow
keys. This allows cycling through the focus within the `FocusScope` in a
closed loop using the arrow keys. Which may be needed by TV application
developers.
Additionally, as in case #160843, `TraversalEdgeBehavior.parentScope`
can be used to allow nested Navigators to traverse focus beyond the
Navigator using arrow keys.
```dart
MaterialApp(
home: Column(
children: <Widget>[
makeFocus(0),
Navigator(
onGenerateRoute: (RouteSettings settings) {
return MaterialPageRoute<void>(
traversalDirectionedEdgeBehavior: TraversalEdgeBehavior.parentScope,
builder: (BuildContext context) {
return Column(
children: <Widget>[
makeFocus(1),
makeFocus(2),
],
);
},
);
},
),
makeFocus(3),
],
),
);
```
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- [x] I listed at least one issue that this PR fixes in the description
above.
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- [x] I added new tests to check the change I am making, or this PR is
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Fixes] where supported.
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e6a65afca4