* Roll Dart to 93d8c9fe2a2c22dc95ec85866af108cfab71ad06.

* Fix analyzer nits

* Try to pin dependency for tools/licenses to convert 2.0.1. Add verbose flag to pub get

* Pin dart to dev.16 to overcome pub issue

* Revert "Try to pin dependency for tools/licenses to convert 2.0.1. Add verbose flag to pub get"

This reverts commit d525a83f4494a511996226d328a5208d4651d46e as it is no
longer needed, was added to diagnose the problem, which turned out to be
a problem with pub in latest dart dev release.

* Fix license hash

* Reintroduce api methods and tests

In https://github.com/flutter/engine/pull/4554 I removed the .packages
file in the frontend_server directory, because it was out of sync with
the pubspec.yaml. It seems like the right solution is to run `pub get`
when we get the dependencies, i.e. when we run `gclient sync`.

Being out of sync is a problem because it means that running "pub get"
in that directory changes what packages are being used, and changes
the `.packages` file, which leads to having to revert changes before
committing code, etc. Having to regularly update this file doesn't
make much sense either, since the files that were missing were files
that are obtained from the network (e.g. the `io` package as used by
the `test` package).

Previously, (see
https://github.com/flutter/engine/pull/3982#issuecomment-323213199),
we did not do this because we did not want the build to call into the
network. This still does not call into the network during the _build_
phase, only during `gclient sync` (which is when all the dependencies
are brought down).

Currently the network dependencies only matter for running tests. We
should make sure this remains the case. Ideally we wouldn't even
depend on those.

* Analysis cleanup of the Dart in the Engine repo

* Update painting.dart

* Update painting.dart

Reland 86430be6 with a fix for Windows build

Cuts 30% from hot-reload benchmarks with `--preview-dart-2`

Fixes https://github.com/flutter/flutter/issues/14092

Scenic doesn't currently support arbitrary shaped frames.

The libtxt Paragraph class now runs the bidi algorithm itself, and each text
run passed to doLayout will be entirely LTR or RTL

Fixes https://github.com/flutter/flutter/issues/7201.

The change from `new Rect.largest()` to `Rect.largest` saves a few
allocations since we'll be using these with every Canvas.

This reverts commit 86430be6 as it
breaks Windows engine buildbot.

Cuts 30% from hot-reload benchmarks with `--preview-dart-2`

* Revert "include portable_unistd.h in directory_asset_bundle (#4542)"

This reverts commit 211150fe.

* Revert "Run Fuchsia apps without flx (#4538)"

This reverts commit 8718438d.

This reverts commit 211150fe.

* Roll Skia to 579f094f1259931c30dfd1623e8e22d74b4a7531

Fixes https://github.com/flutter/flutter/issues/13742

This matches Blink's behavior

Since we've got a vector class, and it has a getter for the magnitude,
why not also a getter for the angle.

* Rolled dart-sdk to bd6cbd1ec7e79730ea1fd8ba01139f4e18a02290

* Updated third_party licenses.

To align with `SemanticsAction`.

This reverts commit d8740c70.

We have a use for this for the internal messaging plugin. Instead of rolling our own, it made sense to add it here especially since it has the mirror functionality (wrap).

Fixes https://github.com/flutter/flutter/issues/13896