This is a blocker for Google roll since we are not at dev4.0:
- Future is not yet part of dart:core.
- Future.sync().then<dynamic>... causes failure without the new keyword.

In my local tests, this should finally fix https://github.com/flutter/flutter/issues/21617

* Don't sync first full kernel file.

* Update the comment

https://github.com/flutter/engine/compare/12315736f9ca...c0e6f6a6e665

git log 12315736f9ca..c0e6f6a6e665 --no-merges --oneline
c0e6f6a6e Roll src/third_party/skia 76bba35cbaa4..46a5f6c28a34 (1 commits) (flutter/engine#6244)
49ef4adad Fix a crash when UILaunchStoryboardName is not specified in Info.plist (flutter/engine#6234)
2a433bc68 Roll src/third_party/skia 34e5e1b387f5..76bba35cbaa4 (2 commits) (flutter/engine#6243)
0c28a093a Roll src/third_party/skia 858f648bdae3..34e5e1b387f5 (8 commits) (flutter/engine#6241)
513f8fbae Roll src/third_party/skia 16322637c477..858f648bdae3 (7 commits) (flutter/engine#6240)
9a7d7215a Roll src/third_party/skia 44215505623b..16322637c477 (10 commits) (flutter/engine#6238)

The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

Previously, the engine did not properly pass the AA flag on ClipRect.clipBehavior. flutter/engine#6199 fixes this and enables AA. However, default AA on clipRects has caused severe regressions in benchmark performance.

To maintain expected performance, we should now default the clipBehavior to hardEdge to disable default AA. This is consistent with any flutter projects that did not previously explicitly set the clipBehavior and should not change app appearance.

Underlying issue with breakpoint was that /var path is a symlink to a /private/var on mac. Because of that breakpoint could not be resolved.

* Revert "Avoid ever creating the WidgetInspectorService outside of debug mode. (#21648)"

This reverts commit eeebd833.

* Remove inspector screenshot service extension.

Replaced about 535 "TBD" translations with the real thing.

Added remainingTextFieldCharacterCountTwo, remainingTextFieldCharacterCountMany, remainingTextFieldCharacterCountFew, to GlobalMaterialLocalizations

Revert "Increase initial delay for scroll_perf_test to try to reduce worst frame stats flakiness." (#21743)

This reverts commit 8cf68731.

https://github.com/flutter/engine/compare/6f459e2f10ca...12315736f9ca

git log 6f459e2f10ca..12315736f9ca --no-merges --oneline
12315736f Roll buildroot to c2764d3620d792e71301dff9a66866029ed200f0 (flutter/engine#6237)
1e622d24d Update to newer Skia font API (flutter/engine#6236)
87b4af095 Roll src/third_party/skia e70aed7066c6..44215505623b (1 commits) (flutter/engine#6235)


The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.

This fixes issues 11940 and 18155.

flutter/engine@6f459e2 Revert "Reapply "Some cleanups enabled by removing support for Dart 1" (#6216)"
flutter/engine@0ded891 Roll src/third_party/skia 1b5ece0f06f4..e70aed7066c6 (1 commits)
flutter/engine@4057327 Roll src/third_party/skia bd6595544171..1b5ece0f06f4 (22 commits)
flutter/engine@838eb3d Improve performance of performance overlay by caching.
flutter/engine@7ac3345 Remove root_surface_transformation from PaintContext

flutter/engine@565a194 Flutter roll for Dart.

flutter/engine@9a173a8 Roll buldroot to a11c4fd9fcc7ad84f465d74461421f3ec790fb99

flutter/engine@51b26f6 Revert "Roll buildroot to eba79bb6db1b50a98ab8ce39def287f7d332a5b8 (#6215)"
flutter/engine@7be4462 Roll src/third_party/skia 2bf7a7bcc67f..bd6595544171 (4 commits)
flutter/engine@54fe12b Roll src/third_party/skia 82bf31003c66..2bf7a7bcc67f (1 commits)
flutter/engine@35ddf87 Roll buildroot to eba79bb6db1b50a98ab8ce39def287f7d332a5b8
flutter/engine@6ed00a8 Roll src/third_party/skia 5518e65d90d7..82bf31003c66 (1 commits)
flutter/engine@8d9e20c Roll src/third_party/skia 3c4d533d8ebd..5518e65d90d7 (1 commits)
flutter/engine@8f39cac Roll src/third_party/skia 7891994e89a3..3c4d533d8ebd (1 commits)
flutter/engine@e3133e0 Reapply "Some cleanups enabled by removing support for Dart 1."
flutter/engine@1fb01f3 Roll src/third_party/skia a2bc1ca21bbc..7891994e89a3 (9 commits)
flutter/engine@f19ee56 Roll freetype2 to 6581fd3e9c8645f01c0d51e4f53893f5391f2bf3

* enable lint unnecessary_new

* fix tests

* fix tests

* fix tests

* Don't set the `vmServices` member variable until it's fully initialized.
* Add a timeout to the future that sends the 'started' event to the IDE

https://github.com/flutter/flutter/issues/16604

flutter/engine@9a173a8 Roll buldroot to a11c4fd9fcc7ad84f465d74461421f3ec790fb99

flutter/engine@51b26f6 Revert "Roll buildroot to eba79bb6db1b50a98ab8ce39def287f7d332a5b8 (#6215)"
flutter/engine@7be4462 Roll src/third_party/skia 2bf7a7bcc67f..bd6595544171 (4 commits)
flutter/engine@54fe12b Roll src/third_party/skia 82bf31003c66..2bf7a7bcc67f (1 commits)
flutter/engine@35ddf87 Roll buildroot to eba79bb6db1b50a98ab8ce39def287f7d332a5b8
flutter/engine@6ed00a8 Roll src/third_party/skia 5518e65d90d7..82bf31003c66 (1 commits)
flutter/engine@8d9e20c Roll src/third_party/skia 3c4d533d8ebd..5518e65d90d7 (1 commits)
flutter/engine@8f39cac Roll src/third_party/skia 7891994e89a3..3c4d533d8ebd (1 commits)
flutter/engine@e3133e0 Reapply "Some cleanups enabled by removing support for Dart 1."
flutter/engine@1fb01f3 Roll src/third_party/skia a2bc1ca21bbc..7891994e89a3 (9 commits)
flutter/engine@f19ee56 Roll freetype2 to 6581fd3e9c8645f01c0d51e4f53893f5391f2bf3

* Ensure that the _childElements map is properly traversed as a sparse list and not inflated with garbage collected children.

* Add tests to ensure Lists/Tabs with KeepAlive children can make large jumps, don't lose children (including after rebuild).

* added shortcuts and delete functionality

* added first test

*  afew chnages

* a few changes

* hope this works

* small change

* small changes

* fixed nits

* final changes:

* fixed initializing formals

* update comment

* minor change:

* added line

* final changes

* random change

* changed function to void

* one more

* removed line

* dis betta work

* final change

* actual final chnge

Fixes #21250

https://github.com/flutter/engine/compare/269880b761a5...d52e5cca03fb

git log 269880b761a5..d52e5cca03fb --no-merges --oneline
d52e5cca0 Roll src/third_party/skia cd9d074578e0..a2bc1ca21bbc (8 commits) (flutter/engine#6211)


The AutoRoll server is located here: https://autoroll.skia.org/r/flutter-engine-flutter-autoroll

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+/master/autoroll/README.md

If the roll is causing failures, please contact the current sheriff, who should
be CC'd on the roll, and stop the roller if necessary.