This is a temporary workaround to unbreak the build. The breakage was
caused by differences in the latest released dev Dart SDK
(2.0.0-dev.64.0) and the version currently used by Flutter
(2.0.0-dev.63.0).
Revert once the SDK has been updated in the engine.
1. Mark perf overlay path as volatile
2. Set sample_margin_width = 0 to get a bar graph instead of saw-tooth.
Previously, the perf overlay itself could be a significant performance
hit and that makes it difficult to profile flutter app.
* Roll dart sdk to 4c9689c1d2da97d0aa25cf16cc90c2e463ad157f
Changes since last roll:
```
4c9689c1d2 [vm] Support pluggable expression compiler for `evaluate` service api call.
d70c38eed8 [Gardening] Mark test as flaky on also non-kernel (legacy)
060ee6769e Make CastStreamSubscription.onData handle a null callback
f7289aa219 Remove specification of naming conventions.
87131780cb Add appendix to spec which specifies JavaScript integer behavior.
dfeaf79cef Fix VM accepting too many overlarge hex numbers in int.parse.
c84a9f46b2 Recompute ClassHierarchy after adding noSuchMethod forwarding stubs
b558a9c2f4 Handle missing compile-time errors
3df126c497 [gardening] Update status for vm-kernel-linux-debug
e22706793d Treat objects with .call as "subtypes" of function types
b960e5a3ed [gardening] Mark standalone_2/io/directory_test as Crash on dartkp/debug
e2d72aad91 Prepare tools/bots/try_benchmarks.sh for Dart 2.
de5f9ea95f Add --use-fasta-parser flags to dartanalyzer and the analysis server.
e2d903c4dc Remove packages/ directory resolution from CFE
aabb78f56a Update checked-in SDK to 2.0.0-dev.63.0 on mac and linux.
bc8d77231d Improve flags documentation, reenable hints in dart2js.
209a602769 Tweak for fixes tests - use orElse to avoid exception.
0e4c158847 Issue 33458. Suggest 'Create Class' Quick Fix for creation without new.
44650cc9eb Pass the location of vm_platform to compile_platform from the commandline.
0bac650833 switch to dart_action until prebuilt Windows Dart VM is updated
82ed18cdb9 Update checked-in Windows SDK to 2.0.0-dev.63.0
2394097e44 Support for including/excluding the same path in ContextRoot.isAnalyzed().
f59389b688 Optimize .runtimeType impact based on usage
ee1f7f5a93 Fix newly reported warnings
afa8ff6292 Add a resource provider that supports file overlays
a63cf8e0cb Add --no-preview-dart-2 flag.
2a396d5315 [vm/intrinsics] Intrinsify 64-bit int typed data.
dd8988c9b2 - Moved all WebGL rendering/drawing constants to synthesized class WebGL. - Removed obsolete Dartium/_blink code.
541dd195bb Enable creating full kernel files in addition to outlines from the bazel worker for kernel.
8e9e8e1da0 Fix various bugs and regularize behavior of returns statements in various kinds of functions.
f1d1da6164 [vm/precomp] Reduce the size of slow-path code in precompiled mode.
b51d3d4146 Key string should be avoided
1e906c3f7e Add no-op entry point for IncrementalCompiler
aeeb7baa96 Change error message to not use imperative tone
309baedc72 Mark some frequently flaky co19 dart2js tests.
1a08341730 Analyzer status file update
ac039abc83 Add option to check if a dill is self-contained
f479435bca - Removed custom handling of fill - it was wrong the method is now overloaded. - Associate the JS class SpeechSyntesisVoice with the correct Dart class (DDC). - Top-level querySelectorAll wasn't generic. - Handle "static" for attributes in the IDLs.
d2a37231b3 optimize await in async* methods in dartdevc
8f0106e490 Update more Analyzer fasta tests
53c2a6f9d5 Cleanup remaining unescape string call sites
1ef4399df0 Run dartfmt --fix for dart2 on pkg/dev_compiler
38eda19be6 Fix resolve_input_uri_test on windows.
5bf6436bc9 Initial implementations of two generators
03bcc495f7 [fuchsia] Migrate process creation to fdio_spawn_vmo
0cf860f361 Remove pub_build_validity test
c015e8d303 Improve invalid string literal error recovery
84f077842b Update CHANGELOG.md for 2.0.0-dev.63 release
7757fa784a [vm] Remove redundant Profiler::DumpStackTrace().
2bc9025be3 Consider initializing formals during top-level type inference
9df6426adb Mark the library analyzer.dart as being deprecated
bd956620fe Remove code that is causing a couple of hints
d99aeb3e13 [kernel] Update Fuchsia suspend to use new API.
6f44d3f208 Issue 2287. Move all, but constructors and fields set in constructors, from StatelessWidget into State.
729e9942bd Support multiple files in messages test.
99575f79ca Split ContextAwareGenerator and its subclasses
41a8b79475 Use the inferred type of const lists/maps to for constant evaluation.
2972ca61f8 Fix continue in invalidation logic
c54a302495 [VM] Evaluate symbols in kernel2kernel constant evaluator in AOT (even in non-const contexts)
4a7ccd5c9a Deleted TODO comment in Scoping
8dca855de1 Specify dynamic type of Futures/... returned from async/... functions
385d825469 Make frontend_server initialize from dill work again
2716b6f9a6 Add test to frontend_server that mimics the flutter benchmarks
17d2839a03 Fixed tests for FF difference.
6779ea0cc6 GN rules: add libraries_specification_uri argument to the compile_platform template.
12b33ada44 [VM interpreter] Support NativeCall kernel bytecode.
db72134f90 [vm/inliner] Add smi return type of clamped convertors.
33feee3b03 [vm/kernel/bytecode] Fix arguments passing in native factory constructors
c30ce41ae6 Add hook to use single-root in fasta scripts and make use of it when creating the dart2js platform files.
34ee27a52d Update to the latest pub
bfb9a4eab8 linter 0.1.53
dfe6385eb0 Fix a Dart 2 runtime cast failure
f7ef66f5b0 Issue 33412. Fix for race condition in knownFiles during search.
aca417a256 Fix test and expected failure.
664f756914 [vm] Reduce maximum new generation size and growth rate.
bd603ba3c6 Record dependencies via CompilerContext
```
Previously the engine would load all embedded fonts listed in the app's
font manifest during startup. This change creates a Skia font manager that
is backed by the engine's AssetManager and can load embedded font assets
on demand.
The txt::FontCollection contains a cache of minikin::FontCollection objects,
which in turn hold a fallback provider that refers back to the txt::FontCollection.
Using a weak_ptr in the fallback provider breaks the circular reference.
