* Gallery scaffolding

* Started RenderSliver

* demo and initial hookup

* Cleaned up demo more and scaffolding basic sliver->widget communication structure.

* works

* states and default indicator building works

* start adding docs

* added an alignment setting optimized the sliver relayout mechanism

* tested a default bottom aligned sized indicator

* Added a bunch of tests

* more fixes and more tests

* Finished the tests

* Add docs

* Add more doc diffing wrt material pull to refresh

* Mention nav bar synergy

* add more asserts

* review 1

* Fix mockito 2 / dart 2 / strong typed tests

* review

* Remove the vscode config

* review

* Add more docs and examples for implementers of RenderSliver

* add more typical scenarios to describe scrollOffset

* review

* tweak a word

Also adds test for interpolating gradient stops.

* pass shadowColor param to SceneBuilder

* add doc comment and diagnostic node for shadowColor

* Add missing shadowColor param

* traverse dependencies and dev dependencies separately

* separate dev and reg deps

* update pubspecs

* add checksum string and update transitive dep string.  Add additional verify command to check checksum

* cleanup comments

* add missing space, quote, run verify-onlu from bot script

* rerun tool with fixed string

* ensure correct working directory and bump versions

* flutter not flutterRoot

See https://help.github.com/articles/licensing-a-repository/#detecting-a-license

* Report an error if compilation times out instead of waiting forever.

* Remove braces

* roll engine version to 6280adbfb1f9f63cdc6179b9b78634add1e4f2e3

* Correctly handle previewDart : false setting in AnalysisServer and
AnalyzeOnce classes.

* Support password fields for a11y

* rename to obscured

* Roll engine to c3ab0c9143029f0267a05b99effbfbd280a4901b

Add another rel device to isLocalEmulator to make working flutter run --release

* rotate expansion icon fully if initial state expanded = true

* add test case for initially expanded

* remove unused import

* Update expand_icon_test.dart

add linebreak

* import dart:math as math

* Add a way to generically go back on both Material and Cupertino scaffold pages

* review

* lint

* review

* Fix text assert text

Fixes #7032

This adds a slider demo with a custom theme to the gallery.

In the process of adding this, I decided to add a text theme to the SliderThemeData, since it's a pain to change the text style on the value indicator otherwise.

This reverts commit c8fd99fb.

* With dart being default, move preview_dart_2 tests to dart1.

* Swap out defaults for preview-dart-2 option in tests. Make dart1 explicit

* Move suffix around

* Rename files

Fixes https://github.com/flutter/flutter/issues/15361

* Use uris for hot reload invalidation.

* Clean up unneccessary conversions

* add final.

* Revert sample change

This is follow-up to https://github.com/flutter/flutter/pull/15537 to make dart1 coverage test happy.