Copy the nnbd SDK so that the analyzer works and can migrate

Include header file without absolute path if the header file belongs to
the same directory as source file.

* null-annotate remaining engine code

* Roll CanvasKit to 0.16.1

Fixes https://github.com/flutter/flutter/issues/58014
Fixes https://github.com/flutter/flutter/issues/56938

* Use multiple shared color arrays

* Use fresh color arrays for computeTonalColors

* Use drawColorInt

* Add TODO to use a flattened array when CanvasKit supports it

https://skia.googlesource.com/skia.git/+log/59f31b143ccd..288ecf60bde8

2020-06-05 egdaniel@google.com Use main command buffer for updateBackendTexture in vulkan.
2020-06-05 michaelludwig@google.com Detect empty clip when difference op clips everything
2020-06-05 csmartdalton@google.com Handle tessellated paths that require more segments than are supported
2020-06-05 mtklein@google.com tiny fixup: depend on :skx
2020-06-05 mtklein@google.com add structure for normal SKX opts
2020-06-05 senorblanco@chromium.org Dawn: fix for abandoned contexts.
2020-06-05 kjlubick@google.com [canvaskit] Fix infrequent crash in SkFontMgr.FromData
2020-06-05 mtklein@google.com remove sse4.1 opts level
2020-06-05 skia-recreate-skps@skia-swarming-bots.iam.gserviceaccount.com Update Go Deps
2020-06-05 skia-autoroll@skia-public.iam.gserviceaccount.com Roll ANGLE from 989c790d4b8b to b10f4b94aa17 (11 revisions)
2020-06-05 skia-autoroll@skia-public.iam.gserviceaccount.com Roll Chromium from 2f74454086a5 to b7bb5840cba2 (462 revisions)
2020-06-05 skia-autoroll@skia-public.iam.gserviceaccount.com Roll SwiftShader from 0711869b5f20 to e3eb327e8c3c (1 revision)
2020-06-05 skia-autoroll@skia-public.iam.gserviceaccount.com Roll dawn from 783cd5a79c8a to 0a6a9d86926e (1 revision)
2020-06-04 jlavrova@google.com ICU optimization

If this roll has caused a breakage, revert this CL and stop the roller
using the controls here:
https://autoroll.skia.org/r/skia-flutter-autoroll
Please CC tdenniston@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

https://dart.googlesource.com/sdk.git/+log/62903873df30..249cb9c974e1

2020-06-05 sra@google.com [benchmark] BigIntParsePrint lint fixes
2020-06-05 bkonyi@google.com [ VM Service / DDS ] Redirect web socket connection requests made to VM Service to DDS
2020-06-05 rmacnak@google.com [vm, gc] Prevent a program with sufficient idle time and dominated by direct old-space allocations from avoiding scavenges for too long.
2020-06-04 scheglov@google.com Implement allowedExperimentsJson for EmbedderSdk.
2020-06-04 rnystrom@google.com Migrate language_2/number to NNBD.
2020-06-04 scheglov@google.com Fix type cast exception in AddExplicitCast.

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

* add nullability annotations to lib/ui/painting.dart

* add nullability annotations to lib/web_ui painting.dat

* add nullability annotations to ui/text.dart

This is causing rendering artifacts on intel.
Co-authored-by: NDavid Reveman <reveman@google.com>

This stops events and platform messages generating errors when the engine has
failed to initialize.

* opening firefox with a given profile

* use .dart_tool for temporary directory. delete the directory if exits before creation