* Drawer fix

* fixed nits

* fixed nits

* fixed nits

* final change

* Drawer fix final

Changes:

- Move the SemanticsConfiguration update from RenderToggleable to each subclass, so that Switch can use toggled.
- Add image, liveRegion, toggled properties to Semantics, SemanticsConfiguration, SemanticsNode
- Added semanticsLabel and excludeFromSemantics to Image (the latter so that we avoid creating a semantics node)
- Added onDismiss semantics action which maps to the modal escape on iOS and dismiss action on Android.
- Added dismiss and liveRegion to snackbar widget
- Updated custom painter semantics to handle image, liveRegion, toggle
- Updated relevant tests to use correct flag/action

Move the notch computation from the FAB to the BAB.

The notch in the BAB (bottom action bar) for the FAB (floating action button) was previously kept as part of the FAB's implementation. This was done to keep the shape of the FAB and the shape of the notch coupled.
That approach resulted in a somewhat complex and 'non Fluttery' mechanism for propagating the notch computation from the FAB to the BAB.

This CL uncouples the FAB and the notch computation.
With the new API the BAB computes its overall shape including the notch using a NotchedShape delegate.

This includes multiple breaking changes:
  * Scaffold.setFloatingActionButtonNotchFor is deleted.
  * The ComputeNotch type is deleted.
  * The hasNotch property of BottomAppBar is deleted.
  * The notchMargin property of FloatingActionButton is deleted.

Quick migration guide from the previous API:

| Previous API | New API |
| ------------------|-------------|
| BottomAppBar(hasNotch: false) | BottomAppBar() |
| Using a FloatingActionButton with: BottomAppBar() / BottomAppBar(hasNotch: true) | BottomAppBar(shape: CircularNotchedRectangle()) |
| Scaffold.setFloatingActionButtonNotchFor(..) | No longer supported |

fuchsia_tester.dart still assumes Dart 1. Previously, it ran tests directly
from source, flutter_platform.dart automatically runs a kernel compile when
operating in Dart 2 mode, but this assumes a functional Dart SDK is available
in the artifacts directly, and fuchsia_tester.dart mocks out the artifacts
directory with an empty temp dir.

Remaining work is:
1. Get the frontend server building as a dependency on Fuchsia.
2. Patch fuchsia_tester.dart to use a valid Dart SDK and frontend server.

This also reverts migration to Dart 2 typedef syntax.

This reverts commit 6c56bb24. (#18362)
This reverts commit 3daebd05. (#18316)

Now that Dart 1 is turned off, reapplying my change to turn on the prefer_generic_function_type_aliases analysis option, and fix all the typedefs to Dart 2 preferred syntax.

Also eliminated the unused analysis_options_repo.yaml file and turned on public_member_api_docs in analysys_options.yaml.

No logic changes, just changing the typedef syntax for all typedefs, and updating analysis options.

Revert "Update typedef syntax to use Function notation and turn on lint for old notation. (#18035)" (#18041)

This reverts commit 32586020.

Fixes #18028

Just changes typedef declarations, no logic changes.

* Add support to move the fab between positions.

* Motion demo for the FAB works between center and end floating.

* Add a Material curve to the offset animation.

* Move the fab position into an object

* Updates to docs

* Updates to docs

* Fix a lint on the bottom sheet type

* Add a ScaffoldGeometry class

* Improve the documentation

* Improve the documentation

* Add a fab motion animator

* Add position and scale animations

* FAB entrance and motion animations work

* Get started on FAB motion

* Make fab animation work properly.

* Change the fab animator to be stored in the state of the scaffold.

* Add a layout test

* Fix spacing being off

* Fix the entrance/exit animation test.

* Add a textDirection to the layout delegate.

* Fix const constructor lint checks

* Add toStrings for the fab positioner/animator

* Add a toString for CurveTween

* Change the fab motion demo icon to a simple add icon.

* Add tests and a custom fab positioner to the demo.

* Do not start the fab's motion animation when the fab is null.

* Adjust the code to pass the new tests.

* Rename for in response to Hans' comment.

* Revert the tabs fab demo

* Use timeDilation, and clean up the animation code a little.

* Clean up the prelayout geometry docs and ctr order

* Cleanup fab transition widget code

* Clean up comments on Scaffold, add cross-references between the two geometries

* Explain the fab motion animation scheduling better

* Add a const to the fab motion demo

* Make the fab animation never jank by keeping track of where to move the fab to in the future.

* Add a default fab positioner constant

* Add space after comma in the demo

* Add boilerplate dartdoc to all const constructors

* Comment improvement

* Rename 'fabSize' to 'floatingActionButtonSize'

* Rename 'fabSize' to 'floatingActionButtonSize'

* Rename 'fabSize' to 'floatingActionButtonSize'

* Clean up the prelayout geometry object's dartdoc

* Clean up the prelayout geometry object's dartdoc

* Remove extraneous comment

* Change possessive uses of Scaffold's to use dartdoc-compatible [Scaffold]'s

* Rename the horizontalFabPadding to an expansion

* Clean up controller cleanup and setState usage

* Animate instead of lerp

* Make the fab position animation use offsets instead of animations

* Streamline the fab motion demo

* Set up the animator to start from a reasonable place when interrupting animations.

* Doc cleanup on the new animation interruption

* Expand some uses of fab and clean up constants

* Expand remaining public uses of fab to floating action button

* Expand remaining public uses of fab to floating action button

* Expand on the documentation for the fab positioner and animator

* Refactor animations to broadcast the position properly.

* Add the ability to turn on and off the fab to the motion demo.

* Remove unused code

* Change the fab animator to animate even when the fab is exitting.

* Remove extra positioner.

* Apps -> Applications in docs

* Explain the scale animation.

* Name the child parameter in the animated builder

* RTL before LTR

* Wrap the AppBar in the example code

* const the fab motion demo name

* Start a test against animation jumps

* Test for jumps in the fab motion animation

* Dont initialize values to null

* Use constants, fix spacing from some of Hans' comments

* Clarify the relationship between fab positioners and prelayout geometries

* Explain the fab animmator a bit better

* Explain the animation progress in the fab animation

* Explain the animation restart better

* Explain the animation restart better

* Explain the prelayout geometry better

* Explain that height is a vertical distance.

* Explain the horizontal fab padding

* Update the scaffold size description to explain what happens when a wild keyboard appears

* Remove print statements

* Update the scaffold geometry with information about it being available at paint time.

* In one step of a transition

* Explain how the top-start fab positioner works

* Explain how the top-start fab positioner works

* Refactor the scaffold layout to just pass a padding instead of a bottom, top, start and end.

* Refactor the scaffold layout to just pass a padding instead of a bottom, top, start and end.

* Action buttons with with custom positioners.

* Add a rotation animation example.

* Use a swap animation to show swapping between two different animations.

* Use a swap animation to show swapping between two different animations.

* Add an example for the size animations.

* 2018 copyright

* Extra empty line

* Return new Scaffold

* Extra blank line fix

* All its contents have been laid out

* Position the fab

* Explain what the scaffold geometry is for.

* Move asserts to different lines

* The scaffoldsize will not

* Initial rename of FabPositioners to FloatingActionButtonLocation

* Rename comments in example to refer to location instead of positioner.

* Rename fabpositioner to location in tests and in the scaffold field

* Finish removing references to positioner in scaffold code.

* Split the fab location and animation out into a separate file.

* Make things more private

* Import foundation instead of meta

* Const curve instead of final.

This allows other code to get the same style without having to know exactly it is computed.

* spelling: accommodate

* spelling: allotted

* spelling: anonymous

* spelling: artificial

* spelling: associated

* spelling: asset

* spelling: button

* spelling: canvas

* spelling: compatibility

* spelling: coverage

* spelling: condition

* spelling: decoration

* spelling: deferring

* spelling: diameter

* spelling: direction

* spelling: displacement

* spelling: dropdown

* spelling: needing

* spelling: environment

* spelling: exited

* spelling: expansion

* spelling: explore

* spelling: families

* spelling: horizontal

* spelling: increment

* spelling: indices

* spelling: internationalization

* spelling: labrador

* spelling: localizations

* spelling: midflight

* spelling: milliseconds

* spelling: minimum

* spelling: multiple

* spelling: multiplication

* spelling: navigator

* spelling: overridden

* spelling: package

* spelling: performance

* spelling: platform

* spelling: porsche

* spelling: position

* spelling: preceded

* spelling: precede

* spelling: precedence

* spelling: print

* spelling: property

* spelling: readily

* spelling: reproducibility

* spelling: rounded

* spelling: scroll

* spelling: separate

* spelling: separator

* spelling: services

* spelling: specific

* spelling: specify

* spelling: synchronously

* spelling: through

* spelling: timeout

* spelling: triangle

* spelling: trivial

* spelling: unusual

* spelling: then

* spelling: vertically

* spelling: visible

* spelling: visited

* spelling: voice

* add a FAB NotchMaker to ScaffoldGeometry

* add a notchMaker to FloatingActionButton

* Initial implementation of BottomAppBar

Mainly includes the notch making logic.
Not yet tested as currently there is no way to make the FAB and the BAB
overlap, once #14368 to lands we could add unit tests to the
BottomAppBar as well.

* use a closeable for clearing the FAB notchmaker

Adds a ScaffoldGeometry class and ValueNotifier for it.
A scaffold's ScaffoldGeometry notifier is held in the _ScaffoldState, and is passed to _ScaffoldScope.
New ScaffoldGemometry objects are built and published to the notifier.

Applies left, right, and bottom media padding (e.g. iOS safe area
insets) around ButtonBar in the material scaffold
persistentFooterButtons.

Note: also fixes a bug wherein bottom media padding was applied even in the
presence of persistent footer buttons.

The material spec states that the keyboard should be positioned on top
of any bottom navigation bar or persistent footer buttons widget(s).

We no longer inset the bottom of bottom navigation bars / persistent
footer buttons by the bottom viewInset.

Body content bottom (and the bottom of bottom sheets) is now determined
by the greater of:
  1. bottom view inset (the keyboard height)
  2. bottom elements (nav bar, footer buttons)
relative to the window max-Y.

In a scaffold, snackbars are positioned above the BottomNavigationBar
and/or PersistentBottomButtons, if present. In such cases, they should
not apply bottom media padding to their widget sub-tree.

Applies any additional bottom, left, and right media padding inside the
snackbar, if present. This accounts for the iPhone X home indicator
widget and horizontal padding for the sensor housing notch in landscape
orientation.

Now that keyboard height is modelled as a (bottom) view inset, migrate
scaffold bottom resizing to use view insets instead of bottom padding,
which, after an engine roll, will only be used for safe areas.

Until the aforementioned engine roll, the keyboard height is still
included in both bottom padding and view insets. As such
resizeToAvoidBottomPadding still drives bottom padding removal until
that roll lands.

Renames _ScaffoldLayout.bottomPadding to bottomViewInset

Also adds a TODO that should have landed with flutter/flutter#13423.

Scaffold bottom padding now applies the maximum of window
viewInsets.bottom (typically used for iOS safe areas) and padding.bottom
(typically used for keyboard height).

Also, extra docs.

Fixes https://github.com/flutter/flutter/issues/13279
Fixes https://github.com/flutter/flutter/issues/2115

I got tired of drive-by spelling fixes, so I figured I'd just take care of them all at once.

This only corrects errors in the dartdocs, not regular comments, and I skipped any sample code in the dartdocs. It doesn't touch any identifiers in the dartdocs either. No code changes, just comments.

Adds `Scaffold#endDrawer` property to supply a second drawer to a Scaffold.

Unlike FractionalOffset, Alignment uses the center as the zero of the
coordinate system, which makes the RTL math work out much cleaner.

Also, make FractionalOffset into a subclass of Alignment so that clients
can continue to use FractionalOffset.

* SafeArea

* AnimatedSafeArea

* AppBar test

* Apply feedback

Fix a bunch of obvious RTL bugs from code inspection.

Fixes #11369

* Notify the completer after the close animation completes on the snackbar

* Review comments

* Fix tests and analyzer warnings

* Fix analyzer warnings

It's redundant as iOS accessibility automatically includes this action on the clock in the status bar.