Implements focus traversal for desktop platforms, including re-implementing the existing focus manager and focus tree.
This implements a Focus widget that can be put into a widget tree to allow input focus to be given to a particular part of a widget tree.
It incorporates with the existing FocusScope and FocusNode infrastructure, and has minimal breakage to the API, although FocusScope.reparentIfNeeded is removed, replaced by a call to FocusAttachment.reparent(), so this is a breaking change:
FocusScopeNodes must now be attached to the focus tree using FocusScopeNode.attach, which takes a context and an optional onKey callback, and returns a FocusAttachment that should be kept by the widget that hosts the FocusScopeNode. This is necessary because of the need to make sure that the focus tree reflects the widget hierarchy.
Callers that used to call FocusScope(context).reparentIfNeeded in their build method will call reparent on a FocusAttachment instead, which they will obtain by calling FocusScopeNode.attach in their initState method. Widgets that own FocusNodes will need to call dispose on the focus node in their dispose method.
Addresses #11344, #1608, #13264, and #1678Fixes#30084Fixes#26704
* some space formattings
* always use blocks in if-else if a block is used
* format spaces in for and while
* allow multiline if conditions
* fix missing space
Adds support for discrete scroll events, such as those sent by a scroll wheel.
Includes the plumbing to convert, dispatch, and handle these events, as well as
Scrollable support for consuming them.
* add trailing commas on list/map/parameters
* add trailing commas on Invocation with nb of arg>1
* add commas for widget containing widgets
* add trailing commas if instantiation contains trailing comma
* revert bad change
* Breaking change which sets the default DragStartBehavior to DragStartBehavior.start and changes WidgetTester.drag and WidgetTester.dragFrom by breaking the moveBy function call into multiple pieces.
* Bugfix: Add platformBrightness to TestWindow.
* Manual engine roll:
cc27cafb8 Implemented Dark Mode for Android (#25525) ([flutter/engine#7488](https://github.com/flutter/engine/pull/7488))
9c05cbcfb Roll src/third_party/dart b53dceadaa..5823be65af (5 commits) 5823be65af [vm/compiler] Continued graph checker development (reland) 8231cdb7a3 [gardening] Update status for issue 35854 db7f848632 [vm] Remove dead BigInt code. 35ab1755f4 Support more type propagation for code-as-ui features 569ee07f91 [vm] Cleanup class finalization checks
ec5e6f6ef Ensure dart2js and kernel worker snapshots are copied out of gen dir ([flutter/engine#7692](https://github.com/flutter/engine/pull/7692))
8b5fa65c4 Roll src/third_party/skia 50ea3c06b80f..2d35a1c87553 (6 commits) ([flutter/engine#7693](https://github.com/flutter/engine/pull/7693))
This implements support for hovering mouse pointers, so that mice connected to Android devices, and ChromeOS devices running Android apps will work properly.
It teaches flutter_test about hover events, which required changing how they are created and used.
Also modifies AnnotatedRegion to allow a region that can be located someplace other than just the origin.
Along with tests for all of the above.
Fixes#5504
