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)

* It's time to #deleteDart1 (#18293)

Eliminates support for Dart 1 in flutter_tools, and drops our Dart 1
benchmarks. All commands now run in Dart 1 mode only.

Eliminates --preview-dart-2 / --no-preview-dart-2 support.

* Fix indentation, remove no longer necessary .toList()

* Only push udpated kernel if >0 invalidated srcs

Several benchmarks started failing during kernel compile:
1. Timeouts:
   * commands_test
   * hot_mode_dev_cycle__benchmark
   * run_machine_concurrent_hot_reload
   * service_extensions_test

2. Kernel compiler crash:
   * hot_mode_dev_cycle_linux__benchmark
   * routing_test

3. Unexpected termination:
   * hot_mode_dev_cycle_win__benchmark

This reverts commit ed63e708.

Eliminates support for Dart 1 in flutter_tools, and drops our Dart 1
benchmarks. All commands now run in Dart 1 mode only.

Eliminates --preview-dart-2 / --no-preview-dart-2 support.

re-write flutter analyze (the single-shot and --flutter-repo) to use the analysis server

Revert "re-write flutter analyze (the single-shot and --flutter-repo) to use the analysis server (#16281)" (#16482)

This reverts commit 2f41ea54.

re-write flutter analyze (the single-shot and --flutter-repo) to use the analysis server

* roll engine version to 6280adbfb1f9f63cdc6179b9b78634add1e4f2e3

* Correctly handle previewDart : false setting in AnalysisServer and
AnalyzeOnce classes.

* have flutter analyze support --preview-dart-2

* review comments

* round 2

* deal with null futures

* review

* review

* review

* review

This reverts commit e13e7806.

Turns out that with this patch, we aren't actually catching all
errors. For example, `flutter analyze --flutter-repo --watch` didn't
report errors in `dev/devicelab/test/adb_test.dart`.

* flutter analyze --watch auto detect if in flutter repo
* move isFlutterLibrary from AnalyzeOnce into AnalyzeBase for use by AnalyzeContinuously
* pass --flutter-repo to analysis server when analyzing the flutter repository
* enhance flutter analyze --watch to summarize public members lacking documentation

* first pass

* improvements

* extract terminal.dart

* rebase

* add default terminal to context

* The analyzer wants the ../ imports in front of the ./ imports

* review notes

* do not forward status if stream is closed
* remove devfs test timeout

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

This ensures that accidental usages of dart:io's
file API don't creep in over time.

This removes direct file access from within flutter_tools
in favor of using `package:file` via a `FileSystem` that's
accessed via the `ApplicationContext`.

This lays the groundwork for us to be able to easily swap
out the underlying file system when running Flutter tools,
which will be used to provide a record/replay file system,
analogous to what we have for process invocations.

With this change, they're run via instance methods on an object
obtained through the context. This will allow us to substitute
that object in tests with replay/record versions to allow us to
mock out the os-layer in tests.

* Remove the workaround that pinned args to v0.13.6
This reverts most of the changes in commit 6331b6c8
* throw exception if exit code is not an integer
* rework command infrastructure to throw ToolExit when non-zero exitCode
* convert commands to return Future<Null>
* cleanup remaining commands to use throwToolExit for non-zero exit code
* remove isUnusual exception message
* add type annotations for updated args package

* convert flutter commands to use ToolExit for non-zero exit code
* add convenience method throwToolExit
* print ToolExit message iff not null

* make showElapsedTime default to true

* support nested progresses

* improve hot reload message

* rethrow