This fixes the hashCode calculation for KeySet<T> so that it doesn't depend on the insertion order of the keys in the set.

The fix involves switching from Set<T> to HashSet<T> internally, so that the iteration order is stable around the hash values of the inserted keys, and not the insertion order. This matters when hashList is called in KeySet<T>.hashCode to build the hash value of the contents of the internal set.

Fixes #38919

git@github.com:flutter/engine.git/compare/78ac65320bde...975a8aa5752e

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2019-08-23 bkonyi@google.com Roll src/third_party/dart 022585cfe2..06d3769ac6 (12 commits)
2019-08-23 skia-flutter-autoroll@skia.org Roll src/third_party/skia 941d0a365045..f17d1c952987 (1 commits) (flutter/engine#11393)
2019-08-23 chinmaygarde@google.com Wire up software rendering in the test compositor. (flutter/engine#11392)
2019-08-23 bkonyi@google.com Roll src/third_party/dart 88c0c11612..022585cfe2 (14 commits)
2019-08-23 yjbanov@google.com preventDefault on touchend to show iOS keyboard (flutter/engine#11390)
2019-08-23 skia-flutter-autoroll@skia.org Roll src/third_party/skia 2a5954140b49..941d0a365045 (6 commits) (flutter/engine#11389)
2019-08-22 stuartmorgan@google.com Allow overriding the GLFW pixel ratio (flutter/engine#11388)
2019-08-22 stuartmorgan@google.com Allow non-resizable windows in GLFW embedding (flutter/engine#11386)
2019-08-22 yjbanov@google.com sync web engine; run web engine tests (flutter/engine#11031)
2019-08-22 garyq@google.com Reland "Track detailed LibTxt metrics with LineMetrics(#10127)" (flutter/engine#11064)
2019-08-22 egarciad@google.com Remove empty line in the pom file (flutter/engine#11382)

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git@github.com:flutter/engine.git/compare/5f03c7e35d71...78ac65320bde

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2019-08-22 skia-flutter-autoroll@skia.org Roll src/third_party/skia 068af9e416cb..2a5954140b49 (8 commits) (flutter/engine#11383)
2019-08-22 stuartmorgan@google.com Switch to an incremental runloop for GLFW (flutter/engine#11368)
2019-08-22 dnfield@google.com Update scenarios readme (flutter/engine#11374)

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TweenAnimationBuilder for building custom animations without managing an AnimationController (#38317)

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2019-08-22 stuartmorgan@google.com Use of App.framework in macOS FlutterDartProject (flutter/engine#11380)
2019-08-22 bkonyi@google.com Roll src/third_party/dart 9fda4c1101..88c0c11612 (12 commits)
2019-08-22 skia-flutter-autoroll@skia.org Roll src/third_party/skia c071fc92cd3d..068af9e416cb (3 commits) (flutter/engine#11379)

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git@github.com:flutter/engine.git/compare/bb8e6e4dbcbb...0345967a1964

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2019-08-22 amirh@users.noreply.github.com Include Java stack trace in method channel invocations (flutter/engine#11361)

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BottomSheetThemeData has an additional field modalElevation which makes it possible to set different elevations between persistent and modal bottom sheets.

Otherwise the error messages would be executed as code when the output
is supposed to be sourced, e.g. $(flutter bash-completion)

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2019-08-22 skia-flutter-autoroll@skia.org Roll src/third_party/skia 42c6af9182d2..c071fc92cd3d (6 commits) (flutter/engine#11372)
2019-08-22 skia-flutter-autoroll@skia.org Roll fuchsia/clang/mac-amd64 from 4uAyd... to NRiBy... (flutter/engine#11371)

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fc27f80a1 1. Update license files to account for the new Dart License file (flutter/engine#11364) (#39028)


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2019-08-22 a-siva@users.noreply.github.com 1. Update license files to account for the new Dart License file (flutter/engine#11364)

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3c695b131 Roll src/third_party/skia 9e081d164c81..42c6af9182d2 (3 commits) (flutter/engine#11366) (#39024)


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* Wire Window.systemGestureInsets to MediaQuery.systemGestureInsets

* Add systemGestureInsets property to TestWindow

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2019-08-22 jonahwilliams@google.com Build legacy web dart sdk (flutter/engine#11360)

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This fixes a breakage in fuchsia where package_config version 1.1.0 is
required but flutter_tools is currently locked to 1.05.

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2019-08-21 chinmaygarde@google.com Dry up fixture comparison in embedder unit-tests. (flutter/engine#11359)
2019-08-21 egarciad@google.com Remove engine hash from pom filename (flutter/engine#11356)

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3606f7bc2 Roll src/third_party/skia 80bff5b3a2d7..9e081d164c81 (16 commits) (flutter/engine#11354) (#39007)


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* Moved the default BinaryMessenger instance to ServicesBinding

This reverts commit 821602ae.

* Added assertion in defaultBinaryMessenger. Also fixed the devicelab tests.

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2019-08-21 dnfield@google.com update sim script (flutter/engine#11355)
2019-08-21 dnfield@google.com Firebase test for Platform Views on iOS (flutter/engine#11350)

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2019-08-21 stuartmorgan@google.com De-dup FILE output for each license (flutter/engine#10945)

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2019-08-21 egarciad@google.com Remove engine hash from the output artifact (flutter/engine#11330)

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