* Update the following packages
- dart-petitparser to 1.7.5
- dart-xml to 3.0.3
- image to 1.1.30
These updates fix some of the strong mode errors we were encountering
while running flutter tests.

This allows other code to get the same style without having to know exactly it is computed.

For example, mention the icon used for the drawer menu in the docs (this helps people writing unit tests); add DefaultAssetBundle sample code.

This fixes the error handling for the packaging script so that it will properly report a failure exit code when it can't find the executable that it's looking for.

Added a test too.

See https://github.com/flutter/flutter/commit/3961306badd313a3f34c5c25a754c1e53a581caf

Fixed the real repaint problem the Slider had (missing addListener), and added tests for it.

Added GlobalKey reparenting test.

Added the ability for the value indicator to slide left and right to avoid falling off the edge of the screen.
It only shifts as much as it can without deforming, but even at large text scales, that is enough to keep the text on the screen.

Updated the formatting on theme_data.dart and others to use longer line length.

Also, removed a color tween that faded the value indicator in as it scaled, since that wasn't to spec.

Fixes https://github.com/flutter/flutter/issues/12445

* Update dependencies with forced upgrade.

Now that https://github.com/flutter/flutter/issues/15261 is fixed, do the update with upgrade.

* Update test package use following upgrade

* Replace addOption(allowMultiple) with addMultiOption

* add fromSpan constructor to Text widget and simple smoke test:

* change fromSpan to rich, clean up comments

* 'directly from' to 'with'

* make sure text styles are applied to either data or textspan. add diagnostic properties for span

* add expectation for text style to test case

* some work on diagnostics and docs

* fix spacing issue and add test for supportsHardwareRendering

* remove extra async tag

* move spacing to prev line

Make flutter test support the --track-widget-creation flag.
Add widget creation location tests. Tests are skipped when
--track-widget-creation flag is not passed.

* Return copied kernel filename.

This fixes 'flutter test --preview-dart-2' crash.

The first child fits on the line if the line can accomodate its width.
After the first child the line needs room for the child's width plus spacing.

This moves toward more consistency in our messaging. Apps are
launched using --debug, so the banner will reflect the build
mode.

* Create frontend compiler in `flutter test` lazily.

This is needed to avoid unwarranted runtime dependencies on Artifacts,
for example when in non-preview-dart-2 mode.
Refactor the compilation-related code into _Compiler class.

This is needed to fix 'flutter test --preview-dart-2 test/all.dart' in dev/devicelab

* Plug TextDirection into box_decoration background gradient

* Add test

* add device.supportsHardwareRendering and display a message if true

* Address some comments

This reverts commit 9d46ed2b.

(libtxt is enabled by default in this engine)

* RenderWrap.performLayout takes should take spacing into consideration when deciding to move to next row/axis

* fix spacing in text

* remove dart:developer import

* remove extra line

Some file I/O is piped from OS processes and never completes,
so without havign a timeout on the recording serialzation, we
end up waiting forever on that I/O to complete.

* Test gradle dependency file generation

* Fix lints, clean up comments, formatting.