This uses @kevmoo's completion package to do command line completion for flutter, and a new command "bash-completion" (with alias "zsh-completion") that will output the necessary shell script setup code, and adds the hidden command "completion" that does the actual completion.

Because it adds a dependency, I also had to do flutter update-packages --force-upgrade.

Fixes #18988.

(second attempt)

This reverts commit 4f1b6604.

We were already skipping the check in `flutter upgrade` but this also spawns `flutter precache` and `flutter doctor` which would still check and potentially output the message.

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

It's required to be set before we detect local engine.

Was broken by #15984

Follow-up comments to #15984

This updates AppContext per the recommendations in #15352

Fixes #15352

When running with --preview-dart-2, host variant of the engine is
required. Simulator builds, like device builds, should resolve
host_RUNTIMEVARIANT_OPTVARIANT, not host_RUNTIMEVARIANT_sim_OPTVARIANT.

Generate the "version" file from git tags.
Remove the old VERSION file and mentions of versions in pubspec.yaml files.
Replace the old update_versions.dart script with a new roll_dev.dart script.
Update "flutter channel".
Update "flutter upgrade", including making it transition from alpha to dev.
Update "flutter --version" and "flutter doctor".

* Fix handling --preview-dart-2 for ios

* final var

Rolling the Dart SDK to 2.0, with associated package updates.  

https://groups.google.com/forum/#!topic/flutter-dev/E22RdKAYjs8

This class lives in the Context and allows callers to "inject"
flag values, where flag values are first extracted from the
command arguments, then from the global arguments as a fallback.

* Move host build check until it's actually used

* Elaborate diagnostic message

This adds --preview-dart-2 flag that enables use of Dart 2.0 Frontend in Flutter tools.

closes https://github.com/flutter/flutter/issues/10534

This way, you can test things even with a VerboseLogger.

This yak shave went as follows:

Fix https://github.com/flutter/flutter/issues/8795 by adding stocks to
the examples README.

Notice the layers entry in that README isn't quite right either.
Update that.

Check the layers/README file is worth pointing at.

Update the layers/README.

Let's run some of the layer tests to see if they still work.

Oops, need to update them to gradle.

Ok let's try running them again.

Oops, sector is broken.

Add a test for sector.

Fix sector. Find you need to add an assert to a const constructor.

Notice we need to turn const asserts on for the analyzer.

Notice the analysis_options files are out of sync with each other and
with the full list of lints.

Turn on the lints that should be on.

Fix the bugs that finds.

Fixes #8562

This adds support for a `--bug-report` flag, which is a recording
that:
  - includes the arguments that were passed to the command runner
  - is zipped up for easy attachment in Guthub issues

Artifacts are now located in a central place.
This will enable us to downlaod artifacts when we need them (instead of
downloading them all upfront).
This also makes replacing sky_snapshot with gen_snapshot easier.