9651 Move the mutators stack handling to preroll

9652 Pipeline allows continuations that can produce to front

9653 External view embedder can tell if embedded views have mutated

9655 Allow embedders to add callbacks for responses to platform messages from the framework.

9660 ExternalViewEmbedder can CancelFrame after pre-roll

9661 Raster now returns an enum rather than boolean

9663 Mutators Stack refactoring

9685 fix Picture.toImage return type check and api conform test.

9698 Ensure that platform messages without response handles can be dispatched.

9713 Explain why OpacityLayer has an offset field

9717 Fixed logLevel filter bug so that filter now works as expected. (#9460)