This modifies the MaterialButton to expand vertically to fit the size of the contained child, no matter what the child widget is. It tries to be as close as possible to the minHeight constraint.

Also updated some doc comments to have headers (extra blank line after first sentence), and to wrap at 80 cols.

Addresses #12311

* Keep incremental compiler state through full restart.

* Add todo

* Add todo

(post-merge followup for #12516)

Fixes #12480

Make material slider respect textScaleFactor

Fixes #5938

Reapply "When parts of the program are changed in a hot reload, but not executed during the reassemble, warn that a restart may be needed." (#12490)

This reverts commit 5e7bcbac.

`flutter run --benchmark` was triggering a different quick bailout path in the VM than `flutter run`. The failure has been fixed upstream.

* Fix restart flow for preview-dart-2 mode.

Restart in preview-dart-2 needs to use kernel file and it has to be complete, rather than incremental kernel file.

* Add curly braces

* Do full compile on restart

* Roll engine to pick up changes to hot reload for preview-dart-2

The initial loading happens on the host, which was building a script snapshot and allowing imports of dart:mirrors. Hot reload happens on the device, which then notices the imports and issues a compile-time error. This change causes programs with imports of dart:mirrors to be rejected during the initial load.

Fixes https://github.com/flutter/flutter/issues/12440

* Keep Icon's subtree structure the same with and without a semanticLabel.

This avoids rebuilding the subtree when a semanticLabel is set/unset.
Also updated some doc comments.

(This is a followup on post-merge comments for #12475)

Fix Italian translations for CUT and COPY.

Fixes #12483

* Update Semantics for SingleChildScrollViews

* refactor

* review feedback

* added assert and comments

* doc

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Fuchsia will soon use a newer version of the Dart analysis server which Flutter code has not been adjusted for yet.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