SkMatrix is deprecating some of its factories. This must moves flutter tests to the new ones.

No expected change in runtime.

Adds a null check before dereferencing in
PlatformPlugin.popSystemNavigator. platformPluginDelegate is allowed to
be null, as it is in the PlatformPlugin(Activity, PlatformChannel)
constructor.

This changes the text handling so that keyboard events are sent to the framework first for handling, and then passed to the text input plugin, so that the framework has a chance to handle keys before they get given to the text field.

This is complicated by the async nature of the interaction with the framework, since GTK wants a synchronous response. So, in this change, I always tell GTK that the event was handled, and if it wasn't, then I re-dispatch the event once we know one way or the other.

https://dart.googlesource.com/sdk.git/+log/97cfd05b3cb3..a37a4d42e53d

2020-12-03 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.12.0-112.0.dev
2020-12-03 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.12.0-111.0.dev
2020-12-03 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.12.0-110.0.dev
2020-12-03 dart-luci-ci-builder@dart-ci.iam.gserviceaccount.com Version 2.12.0-109.0.dev

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