This reverts commit 04ea3183.

This reverts commit e768c92f.

* Update packages.

* Add many more global analyses.

* Catch trailing spaces and trailing newlines in all text files.
  Before we were only checking newly added files, but that means we
  missed some.

* Port the trailing spaces logic to work on Windows too.

* Correct all the files with trailing spaces and newlines.

* Refactor some of the dev/bots logic into a utils.dart library.
  Notably, the "exit" and "print" shims for testing are now usable
  from test.dart, analyze.dart, and run_command.dart.

* Add an "exitWithError" function that prints the red lines and
  then exits. This is the preferred way to exit from test.dart,
  analyze.dart, and run_command.dart.

* More consistency in the output of analyze.dart.

* Refactor analyze.dart to use the _allFiles file enumerating logic
  more widely.

* Add some double-checking logic to the _allFiles logic to catch
  cases where changes to that logic end up catching fewer files
  than expected (helps prevent future false positives).

* Add a check to prevent new binary files from being added to
  the repository. Grandfather in the binaries that we've already
  added.

* Update all the dependencies (needed because we now import crypto in
  dev/bots/analyze.dart).

This switches docs and gallery build and deployment to use Cirrus CI instead of Travis, reapplying the changes from #19925, but updating the Firebase tokens for upload, and refining docs.sh some to limit retries to five times (instead of indefinitely).

This reverts commit a5c2dddd.
Docs push requires different auth options... Will reland shortly.

This adds a Docker image for the linux builds, replacing a lot of the setup code with a Docker build.

Added a docker image build step that has the right gcloud credentials in it.

Also, this finally moves the gallery deployment and docs publishing steps to Cirrus. They were dependent upon some environment setup that was a lot easier to do in Docker than in a setup bash script.