This just fixes some typos, and a small state leak in some of the tests that set env variables.

* Refactor SkiaObjectBox ref counting
* make CkAnimatedImage a Codec
* disallow double dispose; better assertion messages

Reland #22505, now that flutter/flutter#70637 has landed.

Removes references to dart:ui.Window, and switch usages to PlatformDispatcher or SingletonFlutterWindow, as appropriate.

Also remove an obsolete external_view_embedder reference from
AndroidSurfaceFactoryImpl.

Fixes https://github.com/flutter/flutter/issues/70621

This reverts commit 85bfc4c5.

If this roll has caused a breakage, revert this CL and stop the roller
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https://autoroll.skia.org/r/fuchsia-linux-sdk-flutter-engine
Please CC jimgraham@google.com on the revert to ensure that a human
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Documentation for the AutoRoller is here:
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If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/fuchsia-mac-sdk-flutter-engine
Please CC jimgraham@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
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wasm was removed in a recent Dart roll
(https://github.com/flutter/engine/commit/8d332b7ae3205e33e0c7a9b16bb5a04abc9e786f)