* Implement GetAllocationSize for Vertices

* Reflect vertex buffer size in pictures

This reverts commit cc08940e.

Pin the analyzer version as a temporary workaround for https://github.com/dart-lang/sdk/issues/42163 (#18755)

A recent change to the analyzer package introduced an API incompatibility with
the build_resolvers package.  The analyzer package needs to be pinned to an
older version until this is resolved.

Make images contribute to Picture allocation size, more aggressively release references when dispose is called (#18706)

SkImage references get held by both our Image and Picture objects. The GC has no idea about this, and so sometimes pictures look very small when they're actually holding a reference to a large chunk of memory. This patch helps make sure that the GC can more adequately catch the real size impact of Picture objects, and combined with an upstream patch in Dart allows for much more aggressive collection of unused image related memory.

The underlying _updateNode call requires that all parameters be set
non-null. There's a single call site in the framework in
lib/src/semantics/semantics.dart in SemanticsNode.updateWith(). At that
call site, all parameters are either asserted non-null in the
constructor of SemanticsData or defaulted to null, with the sole
exception of textDirection.

The ergonomics of this method are currently pretty ugly and we should
consider migrating most of the defaulting and assertions that we apply
at the call site up to the definition in dart:ui. That work is filed as
https://github.com/flutter/flutter/issues/57720.

https://dart.googlesource.com/sdk.git/+log/3d53df52afb5..54adfeb93f0b

2020-06-02 devoncarew@google.com [nnbd_migration] handle multiple contexts
2020-06-02 zichangguo@google.com [dart:io] Fixes the FileIO performance regression
2020-06-02 srawlins@google.com Analyzer: move built_in_identifier_* tests
2020-06-02 rnystrom@google.com Migrate language_2/metadata to NNBD.
2020-06-02 rnystrom@google.com Migrate language_2/malformed to NNBD.
2020-06-02 srawlins@google.com Analyzer: Mark used extension operators as such
2020-06-02 srawlins@google.com Migrator: Edit the package_config.json file
2020-06-02 scheglov@google.com Clean up verify_sorted_test.
2020-06-02 paulberry@google.com Revert "Remove DartSdk.useSummary."
2020-06-02 jwren@google.com Cleanup format.dart now that recent dartfmt has been rolled forward
2020-06-02 danny@tuppeny.com Enable/disable and register/unregister LSP formatter based on client settings
2020-06-02 danny@tuppeny.com Add LSP support for client-side configuration
2020-06-02 danny@tuppeny.com Minor refactor of LSP server capabilities+init test
2020-06-02 danny@tuppeny.com Improve LSP spec regex to catch didChangeConfiguration method

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/dart-sdk-flutter-engine
Please CC dart-vm-team@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

Adds system mouse cursor to the Android engine.

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/fuchsia-mac-sdk-flutter-engine
Please CC liyuqian@google.com on the revert to ensure that a human
is aware of the problem.

To report a problem with the AutoRoller itself, please file a bug:
https://bugs.chromium.org/p/skia/issues/entry?template=Autoroller+Bug

Documentation for the AutoRoller is here:
https://skia.googlesource.com/buildbot/+doc/master/autoroll/README.md

* runs ios unit tests, if the simulator is already booted.

* address reviewer comments

* changing comments for the Safari desktop tests

* addressing reviewer comments. removing the timeout.

* change mobile browsers ver name for safari.dart

* removing then calback on browser exit, only leaving the exception callback

These are removed in destructors.

This updates the references to `third_party/dart/sdk` to
`third_party/dart/sdk_nnbd`

Fixes: https://github.com/flutter/flutter/issues/58431

* Fix nineslice assertion

* implement SkPath.computeMetrics