* Retain the parent of a SemanticsObject

This fixes the last known crash in iOS accessibility.

* rework memory management

* review comments

* Fix pixel rounding error in the picture layer by first ensuring that
  the texture for the image is at least as big as the next integer size
  along each dimension and using kStrict_SrcRectConstraint while
  drawing the same image. We already select the source subset by
  looking at the cull rect of the picture.
* Decompose the transformation matrix into a series of operations that
  generated the same to calculate the scale at which to rasterize the
  picture. This make the rasterization scale resilient to
  transformations that introduce a perspective component to the
  resultant matrix.
* The scale in the decomposed matrix is now part of the key in the
  cache.
* Raster cache images that could never be rasterized were still taking
  part in the cache. Now, those entries are rejected early on. This
  leads to the sweep after the frame iterating over fewer items.
* Added a unit test target.

Fixes a Fuchsia breakage introduced in
dcfcc925.

If it is not invoked, it triggers a fatal fidl runtime check.

* Roll dart to 64ce51ce4bc3aa4248dba87c44775c9b84bd2b5d (last roll 13 days ago)

* Update license file - ORIGIN was changed because first file was added

***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

Disables auto-capitalization on iOS text fields for TextInputTypes other
than text.

[MA-225][DNO-95] remove message loop handlers when destroying VulkanSurfaceProducer to avoid callbacks on deleted pointers (#3733)

Some keyboards (e.g., on some Samsung devices, SwiftKey) ignore
InputType.TYPE_TEXT_FLAG_NO_SUGGESTIONS and require
InputType.TYPE_TEXT_VARIATION_PASSWORD.

Adds support for requesting a platform keyboard optimised for entering
URLs.

Adds support for requesting a platform keyboard optimised for entering
email addresses.

Fixes a regression introduced in
dcfcc925 in flutter_tester on Linux.

Eliminates logging to stdout on Android -- now using __android_log_print
only.

Eliminates logging to syslog on iOS -- now writing to stdout with the
existing ASL redirection (from platform_mac.mm) only. syslog() wasn't
ever picked up in logs.

This patch is a pre-factoring change before swapping out iOS engine
logging to a flutter-specific mechanism.

* Enable software rendering backend on android. Add "enable-software-rendering" flag.

* Fix variable naming and threading.

[fuchsia] Ensure flutter_apps in the same BUILD.gn have separate scratch directories for building the FLX. (#3720)

Previously, taps were sent to the topmost tap handler in the center of the accessibility frame of the selected element nd therefore might have been handled by a different element than the desired one.

**This is a breaking change on iOS**

Previously, the `paused` state was entered when the application resigned
active status. `inactive` now maps to this status. `paused` now maps to
an app that has been backgrounded.

`inactive` is currently emitted on iOS only and corresponds to iOS's
foreground inactive state.

Current state transitions are:
`resumed` <--> `inactive` <--> `paused`

suspending is currently emitted on Android only and corresponds to the
transition to Android's stopped state.

Current state transitions are:
`resumed` <--> `paused` --> `suspending` --> `resumed`

These transitions may change in future.

Fixes https://github.com/flutter/flutter/issues/10087
Fixes https://github.com/flutter/flutter/issues/10233

I weaksauced

Rather than receiving an ApplicationEnvironment, we now receive a namespace.
Once we have FIDL2, we can plumb the namespace all the way through to Dart.

Android seems to do this by default. This way, if you select a table cell it will read the content of that cell.

* Fix crash in iOS accessbility

Previously, whenever an action would remove the focused element from the screen the app would crash. This change tells iOS to focus the first on-screen element after every change to the semantics tree. This avoids the crash.

In a future iteration, we should tell iOS which element it needs to focus by looking at the sematnics tree (instead of leaving it up to the iOS).

* Better handle the case were the focused element stays on the screen

* review comments

Fixes https://github.com/flutter/flutter/issues/9439

Use AudioServicesPlaySystemSound instead of AudioServicesPlayAlertSound.
This avoids the potential of a system beep on devices without support
for haptic feedback.

Scrollable elements can now be scrolled in accessibility mode and they scroll in the right direction.

Note: App crashes right after scroll finishes (that's a separate problem as the app currently crashes after every action performed in accessibility mode).

* AX fixes for iOS

With this, the accessibility frame (for VoiceOver, etc.) is drawn at the right position around a widget.

* review comments