* Implement

* Don’t scale the fractional offsets since it’s easier to use

* review notes

* fix nit

FlutterCommand.runCommand subclasses can optionally return a FlutterCommandResult which is used to append additional analytics. 

Fix flutter run timing report and add a bunch of dimensional data

backgroundColor -> color
backgroundImage -> image
BackgroundImage -> DecorationImage

If the user specified a non-exact device id, it was producing
an exception whereby we were trying to listen to the
`getAllConnectedDevies()` stream twice.

A NestedScrollView lets you implement patterns where you have a header, tabs,
and additional scrollers inside the tabs.

Fixes #8359

Previously, ScrollPosition did not know about ScrollActivities. However, all
the concrete subclasses of ScrollPosition that we know about need to use
ScrollActivities, so they ended up with a bunch of delegate boilerplate code.

This patch teaches ScrollPosition about ScrollActivities but doesn't have any
opinion about how to start or interact with those activities.

This patch is more refactoring to prepare for nested and linked scrolling.

It causes the test to be flaky, see https://github.com/flutter/flutter/issues/8986.

This will make it easier to implement nested scrolling.

* add a regression test for daemon device notification

* revert event send simplification

* Mark channels_integration_test_ios flaky

* Removed personal dev team from ios code siging

* Removed provisioning profile diffs against other samples

Fixes https://github.com/flutter/flutter/issues/7648

* Add a tile scrolling test to complex_layout app

* - Review comments and fix analyzer failures.

* Use ListView.builder pattern.

Fixes #9612

The enum is called StackFit, so the property name "fit" makes more sense.

Note: In a cross-platform context `Uri.path` is not a valid file path. Allways use `fs.path.fromUri` to convert.

Also, add a timeout so a hung `adb` will not cause the
tools process to hang.

Fixes #9567

`adb` can sometimes hang, which will in turn hang the Dart isolate if
we're using `Process.runSync()`. This changes many of the `Device` methods
to return `Future<T>` in order to allow them to use the async process
methods. A future change will add timeouts to the associated calls so
that we can properly alert the user to the hung `adb` process.

This is work towards #7102, #9567

Also:

 * Add three explicit sizing modes to Stack for non-positioned
   children: loose, expand, and passthrough. (All three are used.)

 * Fix a bug whereby layers would try to paint in the same frame as
   they were removed from layout (but not detached).

 * Fix a bug whereby Offstage wasn't properly marking the parent dirty
   when changing its sizedByParent flag.

 * Explicitly make Overlay expand non-positioned children.

 * Explicitly have InputDecoration pass through the constraints from
   its Row to its Stack children.

Fixes https://github.com/flutter/flutter/issues/8425

* Do not lower-case paths during canonicalization.

This breaks hot reload on some platfroms with case insensitive file systems.

* Add unit tests

This patch reworks some of the guts of scrolling to make it easier to
implement nested scrolling effects. The actually nested scrolling effect
will be included in a later patch.