Remove a target platform override that is no longer needed (I missed this in #51519).

This PR adds the linux and windows target platform enum values, along with automatically setting the defaultTargetPlatform to the appropriate value on those platforms.

Fixes #31366

* unnecessary escapes fixes

* replace some strings with raw strings

* update regexp

* address review comments

Navigator 2.0: Refactor the imperative api to continue working in the new navigation system (#44930)

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

This reverts commit e46671f3.

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).

* Revert "Add visual density to the gallery options (#46090)"

This reverts commit 924efae9.

* Revert "fix analysis (#47594)"

This reverts commit 49c78459.

This PR adds an option to the gallery options that sets the visual density to one of "standard" (the default), "comfortable", or "compact".

[flutter_tool][gallery] Standardize target platform override behavior in tool and update flutter gallery to support it (#46206)

* Relicense Shrine demo to match rest of repository

The Shrine demo was Apache-licensed. The code was mostly
Google-written, with contributions from:

 - Michelle Dudley (@michdud)

 - Abhijeeth Padarthi <rkinabhi@gmail.com> (@rkinabhi)

 - @a14n

I contacted all three, and they confirmed their approval for this
change, as described below.

Abhijeeth Padarthi said by e-mail on Thu, Nov 21, 2019 at 5:48 PM:

> hi Ian,
>
> sure :)
>
> let me know if I need to do anything on my end..

Michelle Dudley wrote by e-mail on Sun, Nov 24, 2019 at 2:07 PM:

> Hi Ian,
>
> That would be ok with me.
>
> Thanks,
>
> Michelle

@a14n said on Discord's Flutter server in the #hackers channel at 10:44PM on Thursday, November 21, 2019:

> @Hixie no problem I agree with this relicensing

* Remove shrine loophole from license checker.

* 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 PR adds TargetPlatform.macOS to the TargetPlatform enum. This allows us to begin implementation of some adaptive UI based on which target platform is desired.

I haven't updated the tests here, that will come in a follow-up PR.

* make BuildContext.{ancestorStateOfType,ancestorRenderObjectOfType,rootAncestorStateOfType} generic

* make BuildContext.inheritFromWidgetOfExactType generic

* make BuildContext.ancestorInheritedElementForWidgetOfExactType generic

* make BuildContext.ancestorWidgetOfExactType generic

* fix snippet

* bump scoped_model on temp version

* update names

* Revert "bump scoped_model on temp version"

This reverts commit d1fcbba028cdb07f44738d1652391692d1ea5ec0.

* address review comments

* fix ci

* address review comments

* repeat the deprecation notice

* fix uppercase

* use of recommanded deprecation syntax

* address review comment

Typo in a title in a gallery demo

This reverts commit 399aebc4.

It contained Apache 2.0 licensed files, which aren't allowed in flutter/flutter

This reverts commit 421bf647.

Was causing severe breakages in Google.