The push to dev-4 allows us to cleanup a few more bits:
  * `api_docs` lint message special casing (lint fixed)
  * `allowedIdentifiersPattern` (lint fixed)

I ran into a case where I was setting minHeight=∞ and then calling
layout() with that constraint, which is all kinds of bad. To try to
catch this earlier, this patch now provides a way to catch constraints
that are requiring infinite values.

We don't _always_ check this because there are valid uses for
BoxConstraints.biggest, e.g. as an additionalConstraint.

* better messaging about windows support

* fix lints

* Add validity checks to create

* Adjust indent

* Remove ScrollableListPainter

* Added OverscrollIndicator, removed OverscrollIndicatorPainter

* add a target for android-x64

* update armeabi-v7a to x86_64

We need to listen to the Scaffold's animation so that we rebuild every time it
ticks so that we can drive our animations.

Fixes #3197

The dartdoc will continue until morale improves.

These columns were secretly re-creating Block in a more complex way. Now we
just use Block directly.

Also, update hello_android to use the new Java class names.

* have flutter precache print if there's no work to do

* tweak precache

We need to pin the version of package:analyzer we use to avoid version skew
within our project.

Do not check for an existing package map if a command is going to run "pub get" to update the package map (#3202)

Also remove a redundant check for the --pub option in the run command

This command explicitly populates the flutter tool's cache of binary artifacts.
Also, teach `flutter create` to update the cache in case its the first command
that a user runs.

This will help folks run pub get after they upgrade their flutter.git
revision.

* Added Scrollbar, removed ScrollbarPainter

* removed a dead import

* updated per review feedback

* Only call dispatch if the widgets State is still mounted

* some docs cleanup

* update styles

* remove unused file

Previously we'd snap to the size of the background widget before resizing to

zero. Now we force the background widget to match the size of the dimissable

widget at the time it was dismissed.



Fixes #3092

Closes https://github.com/flutter/flutter/issues/3149



Closes https://github.com/flutter/flutter/issues/3148

Previously we always used Latin-1.

* move the engine download code to dart

* fix populating the bin/cache/pkg dir

* document libs from sky_services

* scan directory of sky_services for libraries

* simplify error message when sky_services directory not found

* address review comments

Previously we lerped them backwards.



Fixes #2832

Add a command that can capture a Skia picture of a Flutter frame and send it to a file or skiaserve debugger (#3165)