This reverts commit 53e68762.

* allow marking a golden check as flaky

* add matchesFlutterGolden to analyze.dart; no tags for flutter_goldens/lib

* Pause

* ++

* ++

* Analyzer therapy

* Once more with feeling

* Nits

* Review feedback

* Silly oops

* Test progress

* More tests

* Finish

* Nits

* Analyzer

* Review feedback
Co-authored-by: Yegor Jbanov <yjbanov@google.com>

This reverts commit e03f4391.

* Update project.pbxproj files to say Flutter rather than Chromium

Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.

* Update the copyright notice checker to require a standard notice on all files

* Update copyrights on Dart files. (This was a mechanical commit.)

* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.

Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).

* Clean up the copyrights in non-Dart files. (Manual edits.)

Also, make sure templates don't have copyrights.

* Fix some more ORGANIZATIONNAMEs