* Allow specifying and a11y label for Icon widget

This reverts commit e7061698.

This causes preview-dart-2 test failures.

* Roll engine

* Move assert requiring 'this' from initializer to constructor body

* Update test expected message

* Relax regexp to allow wider array of dart uris

Also:

 * Provide a better message when you lerp from infinity to finity
   constraints.

 * Make the striped marker support RTL.

 * By popular demand, dump a warning to the console the first time
   a particular Flex overflows. (Resets on hot reload.)

Fuchsia will soon use a newer version of the Dart analysis server which Flutter code has not been adjusted for yet.

* Add hotReloadInitialDevFSSyncMilliseconds to track how long user have to wait before being able to do first reload.

This stat is significantly different between existing and preview-dart-2 setting (for the latter, this stat is ~3x slower: 13s vs ~4s).

* Remove ws

* Cleanup timer-related code

This updates the bottom navigation bar to be able to handle more general widgets in the place of the label in the bottom navigation bar, so that Text with a textScaleFactor larger than 1.0 will behave nicely in a bottom navigation bar.

It also means that other widgets given instead of a Text widget for the label will work more predictably.

I also vastly simplified the layout logic, eliminating many computations that were not needed, and refactored the build function to use a separate private navigation tile widget.

Also, the color splash animations were coming from the wrong location (they were coming from far to the right of the touched widget), so that works as specified now.

Change PageController#nextPage & #previousPage methods to return Future when the animation completes. (#12299)

* Changed PageController #nextPage & #previousPage to return a Future after completing.

* Removed false statement about returning a Future in PageController#jumpToPage

* Added tests to make sure nextPage & previousPage return Futures.

* Tested that the Futures returned by nextPage & previousPage actually resolve.

* Renaming *pageCalled to *pageCompleted, since that's what it's actually for.

* Force upgrade update packages with improved update process.

* Update packages

* Revert "Update packages"

This reverts commit a37de26d3f4f7f5a15746ff791002625faa3d3c0.

* formatYear

* localize date picker

* tests

* clean-ups

* address comments

* Revert "When parts of the program are changed in a hot reload, but not executed during the reassemble, warn that a restart may be needed. (#12304)"

This reverts commit 90028813.

* fix _debugCheckOwnerBuildTargetExists; sync localizations and tests

* address comments

* Generate Android framework config

* Fix templates

* Moar templates fixing

* Minor tweaking

Fixes #11930

* optimize ThemeData: make it monomorphic, memoize result

* address comments

* RLU cache; fix text theme merging

* use FIFO cache for ThemeData; use HashMap to store inherited widgets

* address comments

Eliminates Invocation.typeArguments override recently introduced and removed in upstream Dart SDK commit:
https://dart-review.googlesource.com/c/sdk/+/10702

Revert "When parts of the program are changed in a hot reload, but not executed during the reassemble, warn that a restart may be needed. (#12304)" (#12406)

This reverts commit 90028813.

This change caused a few bots to fail with 'JSON-RPC error 110: Extension error', which is odd because _getUnusedChangesInLastReload is not an extension.

When parts of the program are changed in a hot reload, but not executed during the reassemble, warn that a restart may be needed. (#12304)

* Make TabBarView/PageView accessible

* review fedback

* update the intellij doctor check to support the m18 plugin version

* update to support multiple package names

Documentation changes, and, in particular, the ability to lerp from
and to any decoration by lerping via null.

Add hidden options --extra-front-end-options and --extra-gen-snapshot-options to flutter tool (#12219)

This CL introduces 2 hidden options to 'flutter build aot' and 'flutter run' for passing arbitrary arguments to front-end server and to gen_snapshot tool when building and running flutter app in --profile or --release modes.

The ability to pass arbitrary options simplifies various experiments, as it removes the need to change defaults and rebuild flutter engine for every tested configuration.

* Drop invisible SemanticsNodes from tree

A node is invisible if it is outside of the bounds of the screen and if it is not merged into its (partially) visible parent.

Also in this PR: only set `wasAffectedByClip` to true if the nodes has actually been clipped.

* Fix other failing tests

* renaming

* review feedback

* more doc

Previously, we used `Alignment`, which was difficult to understand. Now,
we just use an `Offset` scaled to the child's size, which is much easier
to understand.

These now act the way they used to act if both operands are
FractionalOffsets.  Once you mix in some other AlignmentGeometry
objects, everything gets converted to the AlignmentGeometry coordinate
system.

FlutterLogoDecoration should defer to Decoration for what to do when
it doesn't know how to lerp to/from another kind of decoration.

I'm about to add the BoxBorder and BorderDirectional classes to
this new file, but figured it would make review easier if the move
of the existing class happened first.