[a11y] Make sure RenderFractionalTranslation updates its semantics after the translation field is set (#48985)

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).

* 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

This fixes the sample code analysis to treat dartpad snippets in the same way as snippet snippets, which it wasn't until now (the snippet generator was treating them as "samples"), and some errors crept in. This PR also fixes those errors.

Also, added a --verbose option to the sample analyzer.

* Prepare analyze.dart for testing.

* Reorder the file for easier understanding

* Add a test for analyze.dart

* Fix review comments

See #41880 for history.

This reverts commit 1781d5c9.

* more ui-as-code

* address review comments

updates the regex the analyzer uses, so it should be able to recognize expressions such as
const Foo a = Foo(); as "other code" rather than a constructor call.

When we package Flutter, we used to find the "current" tag (which is the version number) by starting at the revision we are building on and looking backwards in time to find the most recent tag. This causes problems on release builds when we failed to tag properly.

This PR makes the packaging script be more strict by requiring the given revision to itself have a tag, but only when we're publishing the result. When we're not publishing the result, it's more lenient, since otherwise we couldn't test packaging on non-release commits.

I also renamed ProcessRunnerException to PreparePackageException, since we were using that exception more generally than just for processes.

* add trailing commas on list/map/parameters

* add trailing commas on Invocation with nb of arg>1

* add commas for widget containing widgets

* add trailing commas if instantiation contains trailing comma

* revert bad change

Adds SHA256 checksums to the released package database, in preparation for showing them on the download website. (I'll update the existing data by hand).

Fixes #28465

This converts all remaining "## Sample code" segments into snippets, and fixes
the snippet generator to handle multiple snippets in the same dartdoc block
properly.

I also generated, compiled, and ran each of the existing application samples,
and fixed them up to be more useful and/or just run without errors.

This PR fixes these problems with examples:

1. Switching tabs in a snippet now works if there is more than one snippet in
   a single dartdoc block.
2. Generation of snippet code now works if there is more than one snippet.
3. Contrast of text and links in the code sample block has been improved to
   recommended levels.
4. Added five new snippet templates, including a "freeform" template to make
   it possible to show examples that need to change the app instantiation.
5. Fixed several examples to run properly, a couple by adding the "Scaffold"
   widget to the template, a couple by just fixing their code.
6. Fixed visual look of some of the samples when they run by placing many
   samples inside of a Scaffold.
7. In order to make it easier to run locally, changed the sample analyzer to
   remove the contents of the supplied temp directory before running, since
   having files that hang around is problematic (only a problem when running
   locally with the `--temp` argument).
8. Added a `SampleCheckerException` class, and handle sample checking
   exceptions more gracefully.
9. Deprecated the old "## Sample code" designation, and added enforcement for
   the deprecation.
10. Removed unnecessary `new` from templates (although they never appeared in
   the samples thanks to dartfmt, but still).

Fixes #26398
Fixes #27411

This reverts commit 71e9bd6f.

This rewrites the sample code analysis script to be a little less of a hack (but still not pretty), and to handle snippets as well.

It also changes the semantics of how sample code is handled: the namespace for the sample code is now limited to the file that it appears in, so some additional "Examples can assume:" blocks were added. The upside of this is that there will be far fewer name collisions.

I fixed the output too: no longer will you get 4000 lines of numbered output with the error at the top and have to grep for the actual problem. It gives the filename and line number of the original location of the code (in the comment in the tree), and prints out the source code on the line that caused the problem along with the error.

For snippets, it prints out the location of the start of the snippet and the source code line that causes the problem. It can't print out the original line, because snippets get formatted when they are written, so the line might not be in the same place.