* eba7a1c90 Roll Dart SDK from e655b9a3839e to b58cfe5ab24e (1 revision) (flutter/engine#21919)

* 512154980 Roll Dart SDK from e655b9a3839e to b58cfe5ab24e (1 revision) (flutter/engine#21920)

* 977537b03 Roll Skia from 418eda2c599a to f9c7b2803461 (3 revisions) (flutter/engine#21923)

* 5bd7260a1 Enable loading snapshots with sound null safety enabled. (flutter/engine#21820)

* 787b9c537 Break the reference cycle between the surface factory and the external view embedder (flutter/engine#21918)

* 9b752790f Revert "[fuchsia] External view embedder will be shared with platform view (#21850)" (flutter/engine#21924)

* 04bf8791f Add plumbing to grab dart entrypoint args on macOS (flutter/engine#21789)

* b8fd0013a Update FLUTTER_NOLINT uses to include issue link (flutter/engine#21921)

* 869d3c8c7 Set strokeCap, strokeJoin, and strokeMiter when resurrecting Paint (flutter/engine#21926)

* 18357a858 Roll Skia from f9c7b2803461 to f60a76e2ac01 (4 revisions) (flutter/engine#21929)

* 49c35b617 Eliminate unnecessary linter opt-outs (flutter/engine#21935)

* 2df836f6e Require that FLUTTER_NOLINT include issue link (flutter/engine#21922)

* f6b8a50ab Roll Skia from f60a76e2ac01 to be8004d2fb6c (1 revision) (flutter/engine#21936)

* 34832cb78 Roll the process_runner package used by the formatter script (flutter/engine#21937)

* 2874fccbb Roll Dart SDK from b58cfe5ab24e to aaab579579be (1 revision) (flutter/engine#21938)

* cac04c4cf Add FML_UNREACHABLE to declare points in code that should never be reached. (flutter/engine#21941)

* fabcc2de2 Roll Fuchsia Mac SDK from _FaRRt69Z... to XZSNobQCT... (flutter/engine#21944)

* 20d3a0764 Collect logs in the background. (flutter/engine#21828)

* 815a1f386 Roll Dart SDK from aaab579579be to 42a0bf548ea3 (1 revision) (flutter/engine#21946)

* 890f01620 [web] Implement ClipOp.difference (flutter/engine#21901)

* 3ea02776e Roll Dart SDK from 42a0bf548ea3 to 675c7165c071 (1 revision) (flutter/engine#21948)

* 56d3da33b Roll Fuchsia Mac SDK from XZSNobQCT... to 9mMCqUXkF... (flutter/engine#21950)

* 1c35cc641 [null-safety] fix type declaration of Picutre._toImage (flutter/engine#21942)

* e9a43c15b Roll Dart SDK from 675c7165c071 to 5c59a47beda7 (1 revision) (flutter/engine#21952)

* 499a70f5e Restore missing call to RuntimeDelegate.OnRootIsolateCreated (flutter/engine#21953)

* f7da9d687 Roll Fuchsia Mac SDK from 9mMCqUXkF... to MR_bRfe8I... (flutter/engine#21955)

* e66e3f535 Roll Skia from be8004d2fb6c to 27f7fe32f49b (1 revision) (flutter/engine#21956)

* d4ac8e6cb Temporarily disabled tests that were using latin and arabic characters (flutter/engine#21971)

* f854cbbfa Specify the Noto Naskh Arabic font to get consistent results in tests using Arabic characters (flutter/engine#21974)

* 43b618e4b Added keyEvent support for iOS 13.4+  (flutter/engine#20972)

* a6857802b Fix the initialization of AndroidSurfaceFactoryImpl (flutter/engine#21977)

* 895940081 [null-safety] fix types of layer code (flutter/engine#21959)

* 9946be45a FlTextInputPlugin: fix memory leaks (flutter/engine#21879)

* bcc557f1b Add multi-step input method support for Linux (flutter/engine#21897)