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.

* 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.

Now that we have thousands of tests, it doesn't make sense to display a separate line for each test. The result is just megabytes of logs that you have to scrub through to find error messages.

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.

This will allow external tools that wrap our test harness to share the
code that generates the test bootstrap.

This change exposed an issue whereby the LocalGoldenFileComparator
was being too strict in its URI handling, so this changes relaxes
that constraint as well (and adds associated tests).

The new values are not ready for use yet inside Google

* Roll engine to e976be13c51448f89107d082ec81e2b6731671fa

* move away from deprecated constants

In order to avoid checking binaries into flutter/flutter,
this comparator can be used to retrieve golden files from
a sibling flutter/goldens repository.

https://github.com/flutter/flutter/issues/16859

This enables support for a `flutter_test_config.dart` configuration file,
which will be discovered and handed the responsibility of running the
test file (thus allowing it to run pre-test setup on a project level).

https://github.com/flutter/flutter/issues/16859

* Add a `matchesGoldenFile()` async matcher that will match
  a finder's widget's rasterized image against a golden file.
* Add support for pluggable image comparison backends
* Add a default backend that does simplistic PNG byte
  comparison on locally stored golden files.
* Add support for `flutter test --update-goldens`, which will
  treat the rasterized image bytes produced during the test
  as the new golden bytes and update the golden file accordingly

Still TODO:

* Add support for the `flutter_test_config.dart` test config hook
* Utilize `flutter_test_config.dart` in `packages/flutter/test`
  to install a backend that retrieves golden files from a dedicated
  `flutter/goldens` repo

https://github.com/flutter/flutter/issues/16859

Fixes https://github.com/flutter/flutter/issues/16496

This avoids notifying the coverage collector that we
completed the test when in fact we timed out, which in
turn avoids a downstream exception caused by the fact
that coverage collector assumes it has a valid observatory
port by which it can gather coverage data.

Fixes https://github.com/flutter/flutter/issues/16839

Finalizers handle the restoration of state. In order to restore
the state correctly, they shouyld be run in LIFO order.

Fixes #16657

* Roll engine to d6d4eec24c38bb06a9b1aef4e70c321d447ba762

Contains the following engine commits:

flutter/engine@1bc0e1b On windows, refer to Dart snapshot directly executable.
flutter/engine@cf6ca32 Revert "Roll Dart to fe606f890b0a311da802c78b0af414a3c2087a79"
flutter/engine@4b45a53 Only make ERROR and FATAL log levels visible by default.
flutter/engine@98f6c2d Fix shell launcher test (dart2 compliant and stop polling)
flutter/engine@75851f0 Roll Dart to fe606f890b0a311da802c78b0af414a3c2087a79
flutter/engine@9495a52 On iOS, try to use ES3, then fall back to ES2.
flutter/engine@d6d4eec Fix broken Linux build
flutter/engine@d15dc76 Fix broken Chromebot build
flutter/engine@c17a629 Breadcrumbs to the wiki
flutter/engine@4eaf2c2 Return raw (unencoded) bytes in Image.toByteData()
flutter/engine@d812a61 Roll src/third_party/skia/ e669bdfad..276886160 (9 commits)
flutter/engine@62aeab7 Call SkSurface::flush instead of getting a backend handle in vulkan_swapchain.
flutter/engine@f4ebb18 Roll src/third_party/skia/ 3462eb034..e669bdfad (54 commits)
flutter/engine@0b7d6be Re-land "do not pause rendering when android view loses focus"
flutter/engine@91dee59 If the rasterizer has a valid surface context, use that to create a snapshotting render target.
flutter/engine@570231b Specify the packages file path when running engine dart tests.
flutter/engine@0b9cef5 Minor update to README
flutter/engine@c386418 Promote line height in text style created from paragraph style
flutter/engine@4e0fbb6 If the test specifies a .dill file, dont make the engine interpret is as source.
flutter/engine@58e84c8 Re-land "Support multiple shells in a single process.
flutter/engine@37e5df0 Remove only use of SkPaint::kGenA8FromLCD
flutter/engine@b7358b3 libtxt: cache font families that are remapped to the default font family
flutter/engine@a530035 libtxt: fix leaks in Skia object reference counting
flutter/engine@0c74fc9 [fuchsia] Fix use-after-free
flutter/engine@b6d2dde [fuchsia] Fix build
flutter/engine@1dd1264 [async] Adapt to libasync API changes.

* Run test platform finalizers in reverse order to ensure that shell is shutdown before trying to delete any temporary files or directories. This fixes "Access Denied" error on Windows (see #16657).

* Handle error count reported by frontend.

Extend compilation result from single string to a structure(string filename and integer error count).

* Use ?.

* Include engine roll with dart sdk roll.

* parse(onError) -> tryParse

* Make '?? throw' more readable and avoid issue with analyzer

* Fix test so it mocks compiler output including errors count

* Report an error if compilation times out instead of waiting forever.

* Remove braces

* Do not encode the server port in the test file

* revert formatting

* add back ignore

* add a default value to serverPort

* address comments

* Update dependencies with forced upgrade.

Now that https://github.com/flutter/flutter/issues/15261 is fixed, do the update with upgrade.

* Update test package use following upgrade

* Replace addOption(allowMultiple) with addMultiOption

Make flutter test support the --track-widget-creation flag.
Add widget creation location tests. Tests are skipped when
--track-widget-creation flag is not passed.

* Return copied kernel filename.

This fixes 'flutter test --preview-dart-2' crash.

* Create frontend compiler in `flutter test` lazily.

This is needed to avoid unwarranted runtime dependencies on Artifacts,
for example when in non-preview-dart-2 mode.
Refactor the compilation-related code into _Compiler class.

* Fix `flutter test --preview-dart-2`  following last dart roll.

Incremental compiler maintains single incremental dill file, so for every test compilation that dill file has to be copied away for execution.

* Fix lints

* Add to Artifacts, and add optional arguments to entry points for flut… (#15185)

Add to Artifacts, and add optional arguments to entry points for flutter run and test to allow for wiring up the same with preview-dart-2 internally

* Changing packages uri here is not necessary

This reverts commit e0f6e626.

Add to Artifacts, and add optional arguments to entry points for flutter run and test to allow for wiring up the same with preview-dart-2 internally

* Run flutter tests in preview-dart-2 mode on travis flutter builds.

* Run dart2 tests on osx. Run dart tests in dart2.

* Fix name camelCase

* Default options to empty array, rather than null

* Troubleshoot failures

* More logging

* Troubleshoot: run single test

* Troubleshoot: run 15 tests

* Troubleshoot: run 15 tests with fix

* Try limit concurrency to 1

* Limit concurrency for preview-dart-2 tests to 4

* Move dart2 tests to allow_failures section

* Reinstate tests_dart_2 shard

* Raise concurrency to 8

* Reuse compiler across multiple test runs

* Allow to switch entry points when recompiling.

Actually use single compiler to incrementally recompile all tests executed by 'flutter test'.

* Remove leftover commented code

* Fix comment

* Lints

This is to fix #14931.