* Fix cachedLastStyle state leak across canvases. Reduce ctx.font reset calls.

* Remove font set test

This change is part of an LSC in Fuchsia, and is a functionality no-op.

Fixes fxbug.dev/50759
Co-authored-by: NGabriel Schine <thatguy@google.com>

This reverts commit b5aedb30 and relands #17712.

Fixes flutter/flutter#53288 and flutter/flutter#41654.

Together with #17791, this reland addresses some of Jim's concerns in the original PR #17712.

The major part of this PR is still the same as the original PR, and the performance / golden image impacts should be the same.

This reverts commit a5e0b2f2.

The way transactions were added changed in
https://github.com/flutter/engine/commit/68fd8334889610af08cbfc2828f91cf14faf3f1d.
This broke rendering using both Metal and OpenGL when no implicit transaction
was present on the transaction stack. The failure models differ based on Metal
vs. OpenGL and iOS/device versions. On older versions of iOS, rendering would
consume memory till exhaustion. On newer iOS versions, rendering would be stuck
(till a timeout). This patch brings transaction management back in line with as
it was earlier and also makes the Metal backend resilient to transactions being
present on the transaction stack at all. Since this is still quite brittle,
transaction management must be moved to IOSSurface as a followup.

Fixes https://github.com/flutter/flutter/issues/55784.

* Revert "Do not register UI-related native functions in secondary isolates (#6401)"

This reverts commit 69ae5694 as it doesn't work when root and secondary isolates run in the same isolate group.

* Confirm it is root isolate that makes UI native calls.

* Fix format, UIDartState reference from Fuchsia source

* No UI isolate check for fuchsia calls

* Fix typo. Remove redundant runtime calls

In order to better support different products on Fuchsia, we should
change performance-sensitive attributes based on config files passed in.
This change does so for `vsync_offset`.

When creating a console on Windows, stdout/stderr aren't wired up to it.
They need to be re-opened afeter the console is created, and that needs
to be done separately in the engine due to the use of static runtime
linking. This provides a helper method that the runner can call when
creating a console so that output will work as expected.

Part of https://github.com/flutter/flutter/issues/53169

* Add TargetPlatform tests

Bundle the validation layers and enable them if --enable-vulkan-validation-layers is specified to gn (#17854)

This is to reduce log spam.

Fixes: https://github.com/flutter/flutter/issues/55966

This functionality is added in issue #41523.  Allows runners to request
the singleton instance of `sys::ComponentContext`, while it remains also
accessible to component-specific code that does not have direct access
to top-level objects.

Fixes #41523