Includes:
* libtxt: add missing dependency for Mac/iOS builds (flutter/engine#4931)
* libtxt: use Helvetica as a fallback font on iOS 8 and earlier (flutter/engine#4930)
* Make Rect.largest match the "largest" rect used in DefaultLayerBuilder (flutter/engine#4926)
* [vulkan] Add VK_ERROR_NOT_PERMITTED_EXT
* Roll buildroot to 8dddd90bf943a8174913564353b30a3b11ee0f7a (flutter/engine#4928)
* Set the asset bundle path when initializing the shell in the embedder API (flutter/engine#4925)
Changes since last roll:
```
ec1e96864 Revert pub roll from recent dart roll. (#4904)
ac552fba4 Port flutter content handler to FIDL2. (#4903)
94cdd8103 Roll dart. (#4902)
af63732de Support `Path.addCircle` (#4783)
564c6a5a9 Add hint to use ninja with goma (#4894)
```
```
Includes:
* libtxt: move to the next run if the current run ends before the start of the line block (flutter/engine#4891)
* Rolled Dart SDK to e3051175192c83fafa3636c0f16d804734bb285a (flutter/engine#4877)
* roll engine version to 6280adbfb1f9f63cdc6179b9b78634add1e4f2e3
* Correctly handle previewDart : false setting in AnalysisServer and
AnalyzeOnce classes.
Includes:
* Provide lookup key to access Flutter assets in the APK (flutter/engine#4785)
* Roll skia and update licenses (flutter/engine#4797)
* libtxt: retain hard line breaks when calculating maxIntrinsicWidth (flutter/engine#4796)
* iupdate engine version to 141176b9004d7b01325629fd45b2ef61b0d00251
* update engine version to f192c59d76c0afe63f2290c3ed76061f00c77cc7
This rolls dart to version 0175f24b2549732d0010708988fd328440c3f956
* Move dart 2 tests back to optional section to allow debugging of a new
regression in the petitParser package.
* Update
* Roll engine to b6df7a637498ca9beda1fa9cd7210e3202ea599f.
Changes since last roll:
```
b6df7a637 Roll dart to 290c576264faa096a0b3206c71b2435309d9f904. (#4771)
a6764dbd5 Add sources for Fuchsia target. (#4763)
2d5900615 [fuchsia] Remove unused header file. (#4769)
9717063b7 Revert "Roll dart to c080951d45e79cd25df98036c4be835b284a269c. (#4767)" (#4768)
9a9814312 Roll dart to c080951d45e79cd25df98036c4be835b284a269c. (#4767)
e74e8b35c [async] Update includes of async headers to new path (#4760)
e2c4b2760 Use Dart 2 camel case constants in the engine Dart libraries (#4766)
9c1e48434 Updates for Fuchsia roll. (#4765)
14c940e27 Switch from fxl::Mutex to std::mutex (#4764)
debf82c0b Roll Garnet (#4759)
5bffdefbb Use weak pointers to the accesibility bridge from objects vended to the UIKit accessibility framework. (#4761)
```
* Roll engine to c88ba37c794f57982374bb53a694301198cad593.
Changes since last roll:
- move generated entry points JSON out of flutter_patched_sdk
- List missing core lib bigint_patch.dart source for new Bigint implementation (#4735)
- Skip over .emf-files. (#4739)
- Roll dart to ee15c8eb689791f6777eb3f6b0a1e9c58ff0671b.
* defaultValue -> orElse
* Revert "Disable a text field test that fails on some Macs with libtxt (#14895)"
This reverts commit aa04a056f39cc9db23878509dc61e0dae7cd7b05.
* Revert "Roll engine to 33b88173f3820690169348859bbdc29133179e0b (#14832)"
This reverts commit 44592238bbf28fe2038bb51ed86e0038ab09a8c7.
* Revert non-engine reverts
Inlcudes:
* libtxt: specifically request the Roboto font in tests and benchmarks (flutter/engine#4675)
* Make Paragraph methods really return List<int> if they are declared as such (flutter/engine#4676)
* Stop using ClassHierarchy.deprecated_incremental (flutter/engine#4678)
* On iOS, render to an offscreen surface to avoid renderbuffer slowdown (flutter/engine#4680)
