* Roll engine dependency forward

* Tests seem to fail with segfault. Trying different engine version to troubleshoot

* Tests seem to fail with segfault. Trying original engine version to troubleshoot

* Tests seem to pass with original engine version. Continue bisecting.

* Tests seem to fail now. Continue bisecting.

* Reverted culprit cl, rolling to that

1. Migrate simulator device log tailing to os_log toolchain
2. When the log tag (component) is available (iOS 11/Xcode 9), filter to
   the set of log lines with tag 'Flutter'.

As of iOS 11 / Xcode 9, Flutter engine logs are no longer recorded in the
simulator's syslog file, which we previously read using tail -f. Instead
they're now accessible through Apple's new macOS/iOS os_log facility,
via /usr/bin/log, which supports a relatively flexible query language.

When run in non-interactive mode, /usr/bin/log buffers its output in 4k
chunks, which is significantly smaller than what's emitted up to the
point where the observatory/diagnostics port information is logged. As a
workaround we force it to run in interactive mode via the script tool.

* Trailing widget override for ExpansionTile

Fixes #11890

* Add a test

* Replaced missing comma

Also, remove some redundant error-checking code that never runs
because we're running these scripts with `set -e`.

This ports the five-second retry interval from flutter.bat to the Bash
version. Failures during "pub get" of the flutter tool are common on
Travis and so this should help Travis reliability if nothing else.

* Add --trace-skia parameter to flutter run

Skia tracing is extremely useful for internal debug, but reduces the
amount of space available in the Dart Timeline buffers.
Disable skia tracing by default and expose them via the --trace-skia
flag.

* Roll Engine to 57a1445a45964d386500c39f5e8d06db060abadb

This reverts commit da0602fe.

* Recreate outputFileName completer, handle process launch errors.

* Fix formatting

* Updated comment

* Things lay out but the effects not right yet

* Remaining functionalities and tests

* one line large title only

* Add more docs

* review

This will make it more tractable to convert them for RTL.

Adds a default title to the Title widget, fixes #6802.

* Show accessibility frame while scrolling

* ++

* fix test

Closes https://github.com/flutter/flutter/pull/12049

Update to reflect https://github.com/flutter/flutter/pull/11751 and https://github.com/flutter/website/pull/663

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