This reverts commit 5c858036.

The k toggle allows switching between canvaskit and html backend at runtime. unfortunately this causes hot restart to break, since the dart_sdk modules stores state at runtime. The recommendation will be to use cavaskit via dart-defines.

Fixes a bug when TextField is wrapped in IntrinsicHeight and visual density is below standard.

[versions] update to latest source span and roll engine to  4b8477d11573d233e6791204191c0090f733b05d (#66136)

Revert "Ensure VmService instance is disposed after failed direct connection attempt (#66123)" (#66164)

This reverts commit 409e994c.
Co-authored-by: Jenn Magder <magder@google.com>

_attemptServiceConnection in FallbackDiscovery would fail if the root
library URI was not a package URI even if the VM service connection
attempt was successful. This resulted in a VM service connection being
left alive, causing DDS to fail its connection to the VM service.

Updated _attemptServiceConnection to ensure the VM service instance is
disposed after a non-connection related failure and to allow for root
library URIs with a file scheme.

* wrap LicensePage's loading widget with cardColor

* Set AnimatedSwitcer's duration in LicensePage to zero

* Remove AnimatedSwitcher

* Add test code for checking color is same

The main.dart.js bypass is not needed now that we have skipWaiting. Additionally optimize the fetch handler so that resources not in the cache skip the service worker altogether.

Fixes #66068

2abe69c60 Roll Dart SDK from 83365979ea85 to e41a6008746d (1 revision) (flutter/engine#21224) (#65987)

Turn the opt-in default for ThemeData.useTextSelectionTheme to true so that everything uses the new TextSelectionTheme by default.