* Revert "Revert "Simplify path handling logic in dependency checker and devFS (#8414)" (#8467)"

This reverts commit 96ba7f76.

* Intentionally use a self-package URI in flutter_gallery

* tests to catch problems with self-package imports

* avoid // ignore: prefer_const_constructors

* address review comments

It's common to have a ChangeNotifier that wraps a single value. This class
makes that easy by providing a generic implementation.

This reverts commit e7bde11c.

Reason: broke hot reload when using "package:" style imports for sources
within the same project.

* Add solution to gradle-dir doctor warning

* Review feedback + properly format strings

Fixes #8395.

* fix a doctor check for webstorm

* fix a missing reference

Also a small formatting fix.

This adds support for a `--bug-report` flag, which is a recording
that:
  - includes the arguments that were passed to the command runner
  - is zipped up for easy attachment in Guthub issues

* Gracefully ignore html content

* Test for less than, consolidate table tests

* Specify missing type annotation

* Add Mike Hoolehan to AUTHORS

* Simplify path handling logic in dependency checker and devFS

Simplification will make it easier to port this to Windows.

* Roll Engine to 0a7b177c330367904597a6129b3eb653d29dfca0

Fixes #8413

* Adds un/selected text styles to the TabBar widget

* Adding documentation on fallback values. Modified fallback on unselectedLabelStyle.

iOS builds rely on package dependencies and associated build artifacts
(pubspec.lock, .packages files) to be up-to-date.

It's common to just want a simple colored box. Simple thing should be simple,
so this patch adds a convenience argument to Continer for creating a box
decoration that is just a color.

Fixes #5555

In some situations, dialogs don't want the barrier to be dismissable.

Fixes #8354

With slivers, the app bar is part of the scroll view. Naively, the overscroll
appears at the beginning of the scroll view, but that's not the desired
behavior. Instead, the app bar should remained pinned to the top of the scroll
view and the overscroll should appear below the app bar, which is what this
patch does.

Fixes #8228

The gradle build scripts can be configured to output different
application IDs for different build types, so we need to examine the
built .apk to figure out the name of the package and activity.

Fixes #8327

It's not just $HOME/.AndroidStudio2.2, it might also be
.AndroidStudioPreview2.3, or .AndroidStudioFooBar1.7, or whatever.

Made the Version parser less throw-happy, and relaxed the directory name
checks to allow for the above.

Fixes #8353.

Fixes #8380

The JDK doesn't put `javac` in the PATH on Windows :(

* Bump to test `0.12.20`.

Some test `0.12.20` highlights:
  * introduces `expectLater()`  that returns a `Future` that completes when the matcher has finished running
  * deprecates the `verbose` parameter to `expect()` and the `formatFailure()` (to be removed in `0.13.0`)

Otherwise:
  * to keep up w/ the deprecation of `verbose`, removes `widget_tester` API to pass `verbose` flag (alternatively we could suppress the warning for now)

* Update stack manipulation.

* Fix framecount.