* Make upscaling images opt-in

* add language version 2.8 in packages/flutter

* enable non-nullable analyzer flag

* Reland "Live image cache" (#51441)

This reverts commit 419a2853.

* Make evict safer

* Revert "Live image cache (#51249)"

This reverts commit e2dcdb60.

* fix tests for other commit

* Revert "Revert "Live image cache (#50318)" (#51131)"

This reverts commit 2f09d601.

* Fix eviction of a pending image

This reverts commit 1602be6a.

Track images available on screen

This normalizes all of the "See also" blocks in comments so that they conform in style.

They all look like this now:

  /// See also:
  ///
  ///  * [MyFavoriteWidget], because it's cool.
  class Foo {}

I removed some useless "See also" blocks, and added commentary to ones that were just "bare" references.

This is my penance for adding so many bullets that are "-" instead of "*". :-)

* 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

No code changes, just comments: I spell-checked all the comments in the repo.

Using custom exception class for network loading error

* add web and io implemenations of network and asset image

* fix foundation import

* update to remove extra asset image indirection

* skip chunk test

* address comments

* disable non-functional test

* disable all golden tests

* address comments

This re-applies the changes that were made in #33697 and #33729,
but which were reverted in #33792 and #33790, respectively due to
the Dart SDK not having received the update within Google yet.
The SDK has now rolled, so these changes can be re-applied.

https://github.com/flutter/flutter/issues/32374
https://github.com/flutter/flutter/issues/33791

This reverts commit 306a09a3.

This updates to use the new HttpClientResponse.compressionState
API that was recently added in the SDK.

https://github.com/flutter/flutter/issues/32374

Updates documentation and non-public API to use American spellings for
consistency with the rest of the codebase.

No changes to behaviour... other than how it's spelt.

This is another step towards supporting image loading
progress notification at the widgets layer.

This adds an `ImageChunkEvent` class along with associated
`ImageChunkListener` callback signature and an `onChunk`
property to `ImageStreamListener`. The events serve to
notify registered listeners when byte chunks are received
while loading an image.

https://github.com/flutter/flutter/issues/32374

The current API was broken in that you registered multiple
callbacks at once, but when you removed listeners, only the
primary listener was used to determine what was removed.
This led to unintuitive cases where the caller could get
unexpected behavior.

This updates the API to add and remove listeners using
a newly introduced [ImageStreamListener] object, a value
object that has references to the individual callbacks
that may fire.

flutter/flutter#24722
flutter/flutter#32374
flutter/flutter#32935

Currently, the fact that NetworkImage uses a static HttpClient
makes it impossible to properly test, as a mock in one test will
be reused in another test. This change fixes that.

https://github.com/flutter/flutter/issues/32374

Make FlutterError objects more structured so they can be displayed better in debugging tools such as Dart DevTools.