* Added IsolateNameServer functionality, which allows for the association
of string names with isolate SendPort ids that can be used to establish
inter-isolate communications.

* Allow specifying the foreground paint

* fix typo

* doc update

* call paint.reset

Support for saving Dart compilation trace on device.

On a Linux host, we were having to convert the type of the bitmap to N32, but we weren't also fixing the channel order to RGBA, so consequently we were getting BGRA when the API was asking for RGBA. This forces the color format to be RGBA when that is what is asked for.

We weren't needing to do conversion on macOS, so macOS was always getting RGBA.

I forgot that the identifiers need to be unique per page for the animation tags.
This makes them unique.

Doc change only, no code.

This updates the documentation for StrokeJoin and StrokeCap to contain animated diagrams that describe their function. The actual diagrams reside in the assets-for-api-docs repo.

Addresses flutter/flutter#18028 for the engine repo, and synchronizes the analysis_options.yaml files between the engine and the flutter/flutter repo.

* split `children` into two ordered lists: traversal and hit test

* address comments

* reduce node object byte size

* link to DebugSemanticsDumpOrder

Fixes flutter/flutter#9226

No logic changes, only links in doc comments.

* update docs for getBounds

* Add computeMetrics suggestion

* better explanation

* Support for TwoPointConical gradients

This reverts commit 919e8c21 as it
breaks flutter gradient_test.

* update docs for getBounds

* Add computeMetrics suggestion

* better explanation

s/`[red]`/_correct color_.

Fixes https://github.com/flutter/flutter/issues/17497

Fixes https://github.com/flutter/flutter/issues/12212

Fixes https://github.com/flutter/flutter/issues/11961

* Roll Dart to 011676641a8b4b77bb372384c712709cbf037675.

Reverts b6be9377 and uses Dart_NewExternalTypedDataWithFinalizer.

* update license goldens

Bug: https://github.com/flutter/flutter/issues/17118

Fixes build break introduced in 33aaf6fc.

* Enable sweep gradients

* Use _matrix4IsValid

* Add assert for startAngle < endAngle

* Use radians for startAngle and endAngle

* Update AUTHORS

* Better assert on matrix4IsValid

This is helpful for some Material Design widgets, which are specified as a semi-transparent color over top of a "material". In some cases, the resulting alpha-blended color can be used instead of compositing an additional shape with an opacity.

This new Color.alphaBlend function mimics the alpha blending function, and creates the resulting combined color. The optimization only works for solid color shapes that have the same geometry, of course.

Fixes regression introduced in https://github.com/flutter/engine/pull/5101.

PlatformMessageResponseDart will wrap large responses in Dart external typed
data objects in order to avoid copying the data into a new buffer.

Previously these objects were created with the Dart_TypedData_kByteData type.
A weak persistent handle is then associated with the ByteData to provide a
finalizer that deletes the raw buffer.  However, the Dart VM could call
finalizer on the ByteData even if references still existed to the Dart ByteBuffer
object backing the ByteData.  The ByteBuffer would then be referencing a deleted
raw buffer.

This PR prevents that scenario by creating a Dart_TypedData_kUint8 object,
attaching the finalizer to that object, and then wrapping it in a ByteData.

* add path measure

* fix typo

* getBound and addPathWithMatrix

* Add myself to Authors, add PathOps

* fix linting issues

* update licenses_flutter to add new files

* Use matrix4 instead of matrix3 for consistency/interop

* put pubspec back

* fix bug in getSegment

* fix typo

* Add return value for PathOp

* refactoring from review

* refactoring from review - still TBD on computeMetrics()

* add doc

* lint issue

* fix computeMetrics, add Path.from

* add missing wireup for clone

* change PathMetrics to iterable, fix bug with angle on Tangent

* prefer std::make_unique

* cleanup docs

* add path measure

* fix typo

* getBound and addPathWithMatrix

* Add myself to Authors, add PathOps

* fix linting issues

* update licenses_flutter to add new files

* Use matrix4 instead of matrix3 for consistency/interop

* put pubspec back

* fix bug in getSegment

* fix typo

* Add return value for PathOp

* refactoring from review

* refactoring from review - still TBD on computeMetrics()

* add doc

* lint issue

* fix computeMetrics, add Path.from

* add missing wireup for clone

* change PathMetrics to iterable, fix bug with angle on Tangent

* prefer std::make_unique

* cleanup docs

* fix iterator bug

* remove unnecessary clone for computeMetrics

* fix some doc issues

* fix PathMeasure iterator, extendWithPath, isClosed, and pubspec.lock

* get rid of orElse; use StateException

* StateError, not StateException

* doc improvements and nits

* add unit tests, fix bugs found during testing

* fix two uncommited doc changes

* one more

* change sign of tangent angle, update docs

* update unit tests for inverted angle

* update tangent to include vector

* Doc fixes

* Fix MSVC compilation and unit test

Platform messages are only support in the UI isolate.  Secondary isolates
do not have a window that can receive incoming messages, and outgoing messages
are not tagged with a destination isolate and thus will always be dispatched
to the UI isolate.

Fixes https://github.com/flutter/flutter/issues/16846

See https://github.com/flutter/flutter/issues/16846

Fixes https://github.com/flutter/flutter/issues/16635

AccessibilityBridge support for edge triggered semantics (iOS + Android)