The old release contained some unused files that caused trouble on the Windows Chromebot.

The last remaining client is complex_layout.

They previously were very sensitive to widgets like LayoutBuilder.

This used to be the logic before I made the tests portable.

Fixes https://github.com/flutter/flutter/issues/7974

Fixes https://github.com/flutter/flutter/issues/7963

* disables all `flutter test` and `flutter drive` tests on Windows as those two commands are not fully implemented on Windows yet
* fixes other failures on Windows

This manual test has used the PageView widget for a while already.

We need to study these benchmark numbers more carefully. See #7937

In particular, we now use ListView in the about dialog.

Required to run tests on Windows bots.

* Small Flutter strong mode cleanup fixes.

These are cases where strong mode down cast composite errors
generally indicated cases that would performance or correctness
issues if Flutter code was run in a strong mode VM.

* Fix Command API so that it is always in terms of Map<String,String>.

* Fix typedef

This prepares us for a CustomScrollView that takes slivers.

...and fix bugs that the tests uncovered.

WRITE TEST FIND BUG

This widget is a start towards replacing PageableList. There are still a number
of features that we'll need to add before this widget can replace PageableList.

* Return null from VM.mainView if no view exists
* Retry in connectToServiceProtocol if a view is not yet available
* Do not explicitly call exit from the benchmarks - it will not cleanly shut down the engine

This update includes the fix for the search box.

These tests would fail sometimes when run locally. Since they happen
to also be the ones that are flaky on bots, maybe there's some
relationship, even though the failure mode on bots is different. In
any case, this removes a variable.

The finder will only match the widget's ValueKey if both have identical
runtime types

This remove a very brittle aspect of flutter drive, whereby it would
assume a known port instead of explicitly finding out what it was.

Fixes #7692 and hopefully fixes the devicelab tests.

Turns out MacOS has a really low open files limit and so if you try to
open EVERY FILE AT THE SAME TIME it falls over.

This just opens the files one at a time, the way we used to back in
the old days.

Fixes https://github.com/flutter/flutter/issues/7661

This patch deploys ScrollView in a number of demos and manual tests.

...now that we have generic methods, their types need to be specified too.

See https://github.com/dart-lang/sdk/issues/28463, which I think is a
regression.

This also fixes the regression introduced by
https://codereview.chromium.org/2559773002 whereby we were no longer
checking any of the lints.