- Remove the unique objects used as slots since we decided 'null' was
fine after all
- Rename 'slot' to 'newSlot' when it's used as an argument to change the
_slot field, to clarify which variable has the newer value
- Remove the RenderObject registry since we'll do listeners a different
way. This also removes handleEvent for the same reason.
- Remove the TODOs for mount/unmount becoming didMount/didUnmount since
the methods do in fact do the mounting/unmounting.
In the old world, we had two ways to bind a Widget tree to a
RenderObject node, one way for RenderView and one mostly untested way
for other cases (it's only tested by the spinning_mixed.dart demo). For
fn3, I made these the same code path.
This patch also introduces GlobalKey, though the GlobalKey logic isn't
hooked in yet.
This is Hello World in the new world:
```dart
import 'package:sky/src/fn3.dart';
void main() {
runApp(new Text('Hello World!'));
}
```
Currently, fling scrolls animate far too long after the display has effectively stopped moving. Use the ScrollSimulation's tolerance property to stop the scrolling roughly when the display stops changing.
- I extracted the BuildScheduler into a separate binding.dart file.
- Various changes to expose private members that are needed by
binding.dart.
- Registering the render objects for event dispatch.
- Convert the tests to use the new binding mechanism.
This doesn't yet have a RenderView or event handling.
Since our build function depends on scrollBehavior.isScrollable, any
time we update scrollBehavior we are implicitly updating our state. As
such, we must do so during a setState() call, or else we won't rebuild
and might not bother to listen to the scroll gestures.
This probably broke when we made Block not listen to gestures if it
wasn't overflowing.
- move _uniqueChild earlier since a comment now mentions it earlier.
- reorder methods in Element to more closely reflect call order.
- change mount to be the place that sets the parent pointer, for consistency.
- make the lifecycleState a purely debug-time thing for consistency.
- make BuildableElement.unmount set dirty to false so that we won't
build unmounted objects.
- rename "updated" to "newWidget" for clarity.
- change how we unmount things so that the slot is reset up to a
RenderObjectElement, but not further, and don't reset the depth.
