* Breaking change which sets the default DragStartBehavior to DragStartBehavior.start and changes WidgetTester.drag and WidgetTester.dragFrom by breaking the moveBy function call into multiple pieces.
* Bugfix: Add platformBrightness to TestWindow.
* Manual engine roll:
cc27cafb8 Implemented Dark Mode for Android (#25525) ([flutter/engine#7488](https://github.com/flutter/engine/pull/7488))
9c05cbcfb Roll src/third_party/dart b53dceadaa..5823be65af (5 commits) 5823be65af [vm/compiler] Continued graph checker development (reland) 8231cdb7a3 [gardening] Update status for issue 35854 db7f848632 [vm] Remove dead BigInt code. 35ab1755f4 Support more type propagation for code-as-ui features 569ee07f91 [vm] Cleanup class finalization checks
ec5e6f6ef Ensure dart2js and kernel worker snapshots are copied out of gen dir ([flutter/engine#7692](https://github.com/flutter/engine/pull/7692))
8b5fa65c4 Roll src/third_party/skia 50ea3c06b80f..2d35a1c87553 (6 commits) ([flutter/engine#7693](https://github.com/flutter/engine/pull/7693))
This implements support for hovering mouse pointers, so that mice connected to Android devices, and ChromeOS devices running Android apps will work properly.
It teaches flutter_test about hover events, which required changing how they are created and used.
Also modifies AnnotatedRegion to allow a region that can be located someplace other than just the origin.
Along with tests for all of the above.
Fixes#5504
* Add support for shadows in text.
* Use dart:ui Shadow as base class for Shadows
* Update lerp definition
* Roll engine 3ffa3629523..84fe4a9f7e24e4 - Text Shadows and update goldens for skia roll.
git log 50c2e69daff4e207c54e463d2304139985c7511c..32f417db0d566d354605305cb29c251276fa65ee --oneline --no-merges
32f417db0 Roll tonic to 077be256142ede39a271385907faadf4fcc62a4d. (#6541)
4ee77256c Revert "Roll Dart to 1f4dfce179c8f05c9e48759300a15e671b88cc10 (#6515)" (#6537)
964acafeb Roll src/third_party/skia 646d917d3c71..c6a17104ad68 (1 commits) (#6536)
d4bae4ca4 Roll src/third_party/skia 2b2c00f6ec36..646d917d3c71 (1 commits) (#6535)
ff93ccf47 Roll src/third_party/skia 681692726fc0..2b2c00f6ec36 (1 commits) (#6534)
a4161c895 Roll src/third_party/skia 23775a2e9736..681692726fc0 (1 commits) (#6532)
116072e46 Roll src/third_party/skia 7435f2553f53..23775a2e9736 (1 commits) (#6531)
ef0b0f6e9 Roll src/third_party/skia bc7a51e79c5b..7435f2553f53 (1 commits) (#6530)
f46b7b971 Roll src/third_party/skia b28db529c866..bc7a51e79c5b (1 commits) (#6529)
9033c3902 Roll src/third_party/skia 7e67041a1428..b28db529c866 (1 commits) (#6528)
e6887a412 Add missing imports for unicode/utf16.h (#6524)
1242f6dfe Roll src/third_party/skia d38382d060ca..7e67041a1428 (2 commits) (#6527)
a1bbea77c Add a no-op platform view layer. (#6505)
2bb3afad8 Roll src/third_party/skia 21bd60daa3f3..d38382d060ca (10 commits) (#6526)
75e875240 Fix the Mac embedder build (#6525)
436f9707b Add version check for dismissable (#6522)
7767c785b Provide a default GL function resolver in the embedder (#6523)
32841dd89 Case-insensitive matching of family names for custom fonts (#6519)
a9076c7e6 Roll src/third_party/skia 419709dbb167..21bd60daa3f3 (11 commits) (#6520)
f2e7441b5 An API for loading fonts from a buffer provided by the application (#6508)
05aac0f27 fix ResourceExtractor npe. (#6461)
cf5a2a145 Roll src/third_party/skia b27a9cf2f4a8..419709dbb167 (16 commits) (#6517)
84fe4a9f7 Re-revert invalid line height tests (#6516)
5f529566c Add support for text shadows (#6385)
e44c10c96 Reland "Share engine layers with the framework" (#6412) (#6468)
ba0449971 Roll Dart to 1f4dfce179c8f05c9e48759300a15e671b88cc10 (#6515)
Adds a Fuchsia compatibility function that allows for connecting to a
specific Isolate by name when running Flutter Driver on a Fuchsia
device. This will check over multiple Dart VM's in an attempt to find
an Isolate by its name.
