Also, make sure that the parent is notified when they change.

Fixes #2298

It's TODONE

We can viewport the content using a ScrollableGrid. Also, we can use the
padding mechanisms of the grid to avoid extra padding widgets.

1. Use the primary color brightness to determine the color of the status bar.
    The status bar overlaps the toolbar, which has the primary color.
 2. Use Roboto for text.

We have these details objects for the same reason we now have drag details
objects: future extensibility.

Fixes #4421

Also:
* Make PaginatedDataTable able to scroll itself horizontally.
* Make drop down buttons support having an explicit text style and icon
  size given.
* Fix a bug with drop-down buttons asserting when opened partly
  off-screen.
* Make sure to pop the drop-down button's route if the drop-down button
  is discarded while the route is up.
* Remove extraneous padding on drop-down buttons. (Couldn't figure out
  why it was there, and it breaks alignment when a drop-down is mixed
  with other text.)
* Some docs improvements.
* Add Route.isActive
* Add a setState() method to ModalRoutes.

I was also going to implement sorting and emptying the cart but the
current data model doesn't make that easy, so I gave up on that. That's
why the TODOs are moved around though.

Fix adding child views to container after changes to dart bindings.

@abarth

Fixes 3544

We were trying to unregister the pointer route twice. Now we only unregister it
once.

Fixes #4341

This lets you build something other than `lib/main.dart`.

* refactor the --resident run option into a separate file

* update daemon to run --resident apps

* re-plumbing daemon start

* send app logs

* update tests

* review changes

* fix test runner

* remove PackageMap.createGlobalInstance; rely on the ctor

* review comments

It's no longer part of the gallery app.

BUG=https://github.com/flutter/flutter/issues/4390

This fix isn't completely statisfying because it has a scaling limit. The ideal
fix would actually viewport the tiles in the grid. However, this fix is much
easier at the moment.

Fixes #4395

Now that there's a new string_scanner in town, we're having dependency
resolution conflict because of flutter_markdown's tight dependency. This
patch loosens the dependency and resolves the conflict.

BUG=https://github.com/flutter/flutter/issues/4321
BUG=https://github.com/flutter/flutter/issues/4349

This patch exposes a convenience function on Scrollable that helps with
updating the scroll extents and ports several clients over to using it.

Assigning to `size` called our intrinsic sizing functions re-entrantly, which
is a destructive operation on TextPainter. Ideally we'd made that a
non-destructive operation, but in the meantime we can fix the tab fading issue
by grabbing the text size before assigning to `size`.

Fixes #4365

The `flutter.buildMode` property now controls whether to build in debug,
profiling, or release.

Fix flutter analyze defaults when files are specified (#4091).

Also, add more dartdoc to widgets.dart.

Turns out we have the same demo in the "Buttons" section now.
We don't need both.

This patch sets a default path for Flutter.framework that's sensible based on
the FLUTTER_MODE.

The hello_services example can now be built both for Android and iOS.

* Pesto demo for the Flutter Gallery app.

* pesto.special.case

Add a FLUTTER_MODE variable to the generated Xcconfig and fix snapshot generation on all targets. (#4362)

Get rid of the DART_EXPERIMENTAL_INTERPRETER_FLAG.

This patch adds some sensible defaults to xcode_backend.sh and documents how to
build hello_services for iOS using Xcode.