* Use l10n tool to generate stocks i18n files

* Rename *_en_EN.arb to *_en_US.arb

* Fix l10n script

There are cases where we have access to the observatory without having a device connection accessible.

This reverts commit 289b4588.

git@github.com:flutter/engine.git/compare/6c763bb551cb...9726b4cb99d3

git log 6c763bb551cb..9726b4cb99d3 --no-merges --oneline
2019-11-06 skia-flutter-autoroll@skia.org Roll src/third_party/skia f3d4109a793b..cdc0c23f1a2e (36 commits) (flutter/engine#13707)
2019-11-06 matthew-carroll@users.noreply.github.com Fix splash screen lookup. (#44131) (flutter/engine#13660)
2019-11-06 gspencergoog@users.noreply.github.com Fix editing selection and deletion on macOS (flutter/engine#13702)
2019-11-06 mouad.debbar@gmail.com [web] Don't send keyboard events from text fields to flutter (flutter/engine#13699)


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Allow ProjectFileInvalidator to be overridden with a different
implementation.

I stole this from https://github.com/flutter/flutter/pull/39217.

git@github.com:flutter/engine.git/compare/05ab04dbe8cf...6c763bb551cb

git log 05ab04dbe8cf..6c763bb551cb --no-merges --oneline
2019-11-06 fmil@google.com [fuchsia] Temporarily disable intl provider (flutter/engine#13696)
2019-11-05 matthew-carroll@users.noreply.github.com Fix plugin registrant reflection path. (#44161) (flutter/engine#13698)
2019-11-05 darrenaustin@google.com Added Semantic header support on Android. (flutter/engine#13262)


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* added new lfecycle state

* update

* update

This missed some plugins that _do_ support the v1 embedding
(shared_preferences as one known case) so caused unexpected breakages.

This reverts commit b94c1a41.

git@github.com:flutter/engine.git/compare/7b968ff95ff1...0928c1af2f45

git log 7b968ff95ff1..0928c1af2f45 --no-merges --oneline
2019-11-05 garyq@google.com Add 'Cough' test font and support multiple test fonts. (flutter/engine#13649)
2019-11-05 skia-flutter-autoroll@skia.org Roll src/third_party/skia 4cc2dc64ff13..4a4f34b76f3a (19 commits) (flutter/engine#13637)


If this roll has caused a breakage, revert this CL and stop the roller
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This makes the flutter tool download the debug symbols for Flutter and Dart runners to be used in Fuchsia dev environment.

This reverts commit a214b462.

* Add Material Study app Rally to examples

Adds the CupertinoContextMenu widget for iOS 13 support.

Fixes #42049.

git@github.com:flutter/engine.git/compare/e73c9c8f6bd5...7b968ff95ff1

git log e73c9c8f6bd5..7b968ff95ff1 --no-merges --oneline
2019-11-05 chinmaygarde@google.com Ensure that the CAMetalLayer FBO attachments can be read from. (flutter/engine#13643)
2019-11-04 47866232+chunhtai@users.noreply.github.com Revert "Added new lifecycle enum (#11913)" (flutter/engine#13632)
2019-11-04 47866232+chunhtai@users.noreply.github.com Added new lifecycle enum (flutter/engine#11913)


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git@github.com:flutter/engine.git/compare/0a8bd9dd6fbb...e73c9c8f6bd5

git log 0a8bd9dd6fbb..e73c9c8f6bd5 --no-merges --oneline
2019-11-04 skia-flutter-autoroll@skia.org Roll src/third_party/skia 8e083eee8ece..4cc2dc64ff13 (1 commits) (flutter/engine#13543)
2019-11-04 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from ggsQ5... to XcaoM... (flutter/engine#13535)
2019-11-04 yjbanov@google.com fix getBoxesForRange for zero-length ranges (flutter/engine#13483)
2019-11-04 bkonyi@google.com Roll src/third_party/dart bbe2ac28c9..ab5cf0f854 (73 commits) (flutter/engine#13614)
2019-11-02 skia-flutter-autoroll@skia.org Roll src/third_party/skia 283ec65f632a..8e083eee8ece (32 commits) (flutter/engine#13489)
2019-11-02 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from FKqQ_... to ggsQ5... (flutter/engine#13490)
2019-11-02 xster@google.com Release shim bindings when detaching (flutter/engine#13432)
2019-11-01 gw280@google.com Add fuchsia.intl.PropertyProvider to our services on Fuchsia (flutter/engine#13486)
2019-11-01 fmil@google.com [dart] Makes the intl services available (flutter/engine#13460)
2019-11-01 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/linux-amd64 from 866GG... to dhwMR... (flutter/engine#13475)
2019-11-01 skia-flutter-autoroll@skia.org Roll fuchsia/sdk/core/mac-amd64 from JngMB... to FKqQ_... (flutter/engine#13477)
2019-11-01 skia-flutter-autoroll@skia.org Roll src/third_party/skia 809ec77893be..283ec65f632a (14 commits) (flutter/engine#13472)
2019-11-01 dnfield@google.com Request a reattach when creating the text input plugin on Android (flutter/engine#13474)


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*Starting with arb files in lib/l10n, the tool creates the following by default:
1. An AppLocalizations class containing:
- an `AppLocalizationsDelegate`
- a `supportedLocales` property that returns a list of all supported locales.
- a `localizationsDelegate` property that returns a list containing this delegate along with `GlobalMaterialLocalizations.delegate`, `GlobalCupertinoLocalizations.delegate`, and `GlobalWidgetsLocalizations.delegate`.
2. One Dart `message_<locale>.dart` file for each arb file, as well as a `messages_all.dart` file that performs the locale message lookup. The tool infers the locale of each arb file from the @@Locale property or the arb file's name.

* Adjust and refactor all FlatButton tests into its respective file

initalValue should be initialValue

SliverAppBar - Configurable overscroll stretch with callback feature & FlexibleSpaceBar support (#42250)

* remove Source.behavior, fix bug in depfile invalidation

* more cleanup of assets

* Add skip

* address comments

* Update build_system.dart