Diagnostics object is.

Fix a bunch of obvious RTL bugs from code inspection.

Removed the legacy --plugin option from flutter create.  Fixes #11815.

* only tap on widgets reachable by hit testing

* use FractionalOffset

* added tests

* check finder finds correct widget

* undo unintentional changes

* address comments

* style fix

* add Directionality in test

* fix analysis warning

* Refactor SemanticsData and SemanticsNode to use Diagnosticable.

* Switch toStringDeep to take named parameters.

* Make an app's supported locales configurable

* Added an supportedLocales.isNotEmpty assert

* WidgetsApp no longer const because supportedLocales.isNotEmpty

* updated per review feedback

* tweaked dartdoc to restart the build

* updated per review feedback

* Updated per review feedback

* ++

* ++

* ++

* ++

* ++

* dart docs

* test fix

* undo unintended change

* fix test

* fix test

* review feedback

...rather than only wrapping the children.

Also, improvements to Banner to better support RTL, and mock_canvas to
make debugging things easier.

Notice that the default alignment for Stack needs to know the
directionality.

* Rename BannerLocation enum values

 * topLeft -> topStart
 * topRight -> topEnd
 * bottomLeft -> bottomStart
 * bottomRight -> bottomEnd

These names will make it easier for us to adjust the location of the
banner in right-to-left mode.

See the discussion on flutter-dev.

* Add RTL support for Banner

Fixes #11905

* Selectively apply margin between middle and leading

If ToolbarLayout does not have a leading widget, we should not put a margin between leading and middle areas since it ends up being blank space that looks odd. Fixes https://github.com/flutter/flutter/issues/11963

* Fix the failing test which is a good test case for missing leading widget

This roll includes:
https://github.com/flutter/engine/pull/4069 - Return generated kernel filename on incremental compilation results
https://github.com/flutter/engine/pull/4070 - Updates for the dart:fidl.internal rename and split
https://github.com/flutter/engine/pull/4072 - Set the is_official_build flag that disables GR_TEST_UTILS in Skia
https://github.com/flutter/engine/pull/4067 - Define which SemanticsNodes are a11y focusable on Android

* Include instructions to build host configuration for preview-dart-2

* Space before lparen

This was introduced to suppress libMobileGestalt noise originating from
libsystem_asl.dylib. Commit 39680ebf
suppresses all application log messages not originating from the
app/engine iteself on iOS 10 and above. Since the log message in
question is only emitted on devices running iOS >= 10.3.0, this
blacklist no longer necessary.

On iOS 10 and above, suppress engine log messages from system components
other than Flutter. This eliminates a large amount of keyboard/plugin
related noise during edit-refresh development.

This patch just fixes the next and previous buttons to be in the proper
place. There might be other issues with the DatePicker, but this one was
obvious.

See #11377

This roll caused performance regressions in benchmarks:
* complex_layout_scroll_perf
* flutter_gallery_transition_perf

This reverts commit f430a45a.

* Roll engien to 79332e5c42555875c7070c33810dab3f0012ace1

* Remove deprecated @proxy

* Roll engine to ceb6d05c2fb3bd5c31a25d4b08be9fd97b55a446

Checksum validation is intended only as a performance improvement.
Checksum de-serialization errors (typically framework version mismatch) are
expected on framework updates and shouldn't be user-visible except for
informational purposes when --verbose is set.

ios-deploy 1.9.2 includes fixes for a common source of Xcode breakage
(flutter/flutter#4326) with Xcode 8.3.3 + iOS 10.3.3, and is required to
to support Xcode 9 (flutter/flutter#11875).

Opening Xcode is no longer sufficient to enable develop mode in Xcode 9.
Update the message to run the command-line tool. Alternatively users can
launch an app in the Xcode debugger to do this.

* getOffsetToReveal deals with pinned slivers

If a Sliver can potentially be pinned at the edge of a viewport, getOffsetToReveal will take that into account and scroll further up/down to ensure that the object to reveal doesn't end up covered by a pinned sliver.

This is important for accessibility scrolling with app bars.

Since how much a pinned sliver is covering is dynamic (it can change with scroll offset, etc), getOffsetToReveal deals with the worst case and tries to ensure that the object to uncover is visible when the pinned slivers are at their max pinned extent.

* name fixes

* review feedback

* typos

* renaming

* fix analyzer

* fix test

* analyzer fixes

Fixes #11855