* Fix remaining ftl->fxl conversions

The previous scripting pass at this did not account for objective c file endings

* Update tonic DEPS reference to the post-fxl version

* Various iOS a11y fixes

* undo

* review comments

* review comments

 - Assumes only the Dart VM is interested in idle notification.
 - Gives the VM the time remaining in each frame.
 - Gives the VM 100ms if there is no pending frame.

Issue flutter/flutter#9594

This repository contains FTL now in the Fuchsia build.

Update ICU to ToT and ensure that slimmed down versions of data files are shipped on the mobile platforms. (#4005)

This reduces the size of the ICU data files from 10.3 MB to 6.6 MB (uncompressed). Also allows us to remove version specific hacks from libTXT and dependencies.

Let the FlutterAppDelegate's messenger be customizable if the rootViewController isn't a FlutterViewController (#3916)

* Customizable messenger

* rename

On iOS, backgrounded applications are not permitted to execute GPU work.
See [1].  When backgrounding the application, we now tear down the
underlying iOS render surface, and re-create when the app returns to
foreground.

See [2] for a Technica Q&A on GL-related crashes when rendering is
attempted by a backgrounded application.

[1]: https://developer.apple.com/library/content/documentation/3DDrawing/Conceptual/OpenGLES_ProgrammingGuide/ImplementingaMultitasking-awareOpenGLESApplication/ImplementingaMultitasking-awareOpenGLESApplication.html#//apple_ref/doc/uid/TP40008793-CH5-SW1
[2]: https://developer.apple.com/library/content/qa/qa1766/_index.html

For consistency with Android, when the engine receives a
TextInput.setEditingState message from the framework, and the text has
changed, we now send a TextInputClient.updateEditingState message back
to the framework with the updated state from the engine. The framework
currently relies on this behaviour to trigger onChanged events in
certain scenarios (e.g., on tapping Paste in the selection controls).

Note: it may be more desirable for the framework to trigger the
onChanged calls without relying on the return message from the engine,
but this change ensures consistent behaviour across iOS and Android
until we've evaluated the pros/cons of such an approach.

Create platform API for first frame callback. Use for defer hiding splash screens on Android and iOS (#3956)

* Add back launch screen view until first frame on iOS

* improvements

* Move callback plumbing from ios surfaces to the gpu rasterizer. Didn’t wire java JNI yet.

* Android JNI

* Fix ios reference count and let android engine manage a view on top with launch screen

* Hook up Android activity and view

* review notes

* review notes

* Move thread switching upstream. Use weak references for callbacks.

* Some clean up

* fix (with squashed debug stuff)

* clean up

Revert "Revert "Reland "Run Flutter on iOS and Android with color correct Skia (#3826)" (#3878)" (#3895)

This reverts commit 1db18a40.

Adds handling for the autocorrect field on TextField on iOS devices.

This reverts commit 2d9155e1.

Fixes a regression with semitransparent images (flutter/flutter#11169)

Related to https://github.com/flutter/engine/pull/3870.

* Revert "Revert "Reland "Run Flutter on iOS and Android with color correct Skia" (#3818)" (#3823)"

This reverts commit db8d8a99.

* Fix test code to match internal API change

This reverts commit 2650f529.

* Revert "Revert "Run Flutter on iOS and Android with color correct Skia (#3743)" (#3775)"

This reverts commit cfe70e07.

* Enable sRGB on IO thread, too

* Add 4444 as a fallback rendering mode

* Use bare ptr to SkColorSpace (not sk_sp) in PrerollContext

This reverts commit ffe8181f.

Both the following, which we also support, are deprecated in UIKit:

* `application:handleOpenURL:`
* `application:openURL:sourceApplication:annotation:`

Expose performActionForShortcutItem call to all registered plugins so we can handle quick actions (#3763)

* Expose performActionForShortcutItem call to all registered plugins so we can handle quick actions

* Should return BOOL not void

* clang-formatted

* Adding SemanticsFlag.isSelected

* typo

* Run Flutter on iOS and Android with color correct Skia (#3716)

***Turns on color correct rendering for Android and iOS
***Communicates dst color space to raster cache
***Turns on color space aware image decoding

Test:
***color_testing_demo on Pixel XL
***flutter_gallery on iPad Mini and iPad Pro (haven't figured out how to run manual_tests on iOS)

TODO:
I needed to split up this CL somewhere. These are follow-up tasks.
***Make desktop backends color correct
***Make debugging tools (ex: encoding frames to png) preserve color space
***Investigate using UIKit API to allow iOS to fine tune color space of rendered content

* Retain the parent of a SemanticsObject

This fixes the last known crash in iOS accessibility.

* rework memory management

* review comments

***Turns on color correct rendering for Android and iOS
***Communicates dst color space to raster cache
***Turns on color space aware image decoding

Test:
***color_testing_demo on Pixel XL
***flutter_gallery on iPad Mini and iPad Pro (haven't figured out how to run manual_tests on iOS)

TODO:
I needed to split up this CL somewhere. These are follow-up tasks.
***Make desktop backends color correct
***Make debugging tools (ex: encoding frames to png) preserve color space
***Investigate using UIKit API to allow iOS to fine tune color space of rendered content