This patch adds `@checked` everywhere is needed to remove the
`strong_mode_invalid_method_override` strong mode error.

* commit intellij project metadata

* move metadata to the top level

* delete dev/intellij

The only change here is that if we run off the end of the loop in a way
that previously would have just hung, we return silently.

This will make it easier to switch to SemanticsUpdateBuilder.

This change might make our grammar less perfect, but it will increase our
sanity.

Fixes https://github.com/flutter/flutter/issues/5763

RC1 patch release.

Fixes https://github.com/flutter/flutter/issues/6154

Fixes #6215

* Bump Dart SDK to `1.20.0-dev.10.0`.

`1.20.0-dev.10.0` corresponds to `1.20-RC0`.

* pubspec.lock cleanup

* check for pubspec.lock existence

* cleaned up conditional remove

* make flutter create less chatty

* output generated file count; mention lib/main.dart

This widget now lives in Mozart:

https://fuchsia.googlesource.com/mozart/+/master/lib/flutter/child_view.dart

This patch removes the Mozart dependencies from object.dart and
layer.dart, which will make it easier for us to move the Mozart
dependencies purely into the Fuchsia tree.

* Update ISSUE_TEMPLATE.md

Let's move the flutter doctor stuff last since it's usually not as critical as the logs.

* Update ISSUE_TEMPLATE.md

Fixes #988

The diagnostic port forward can be arbitrarily assigned and typically
is not the default

Fixes https://github.com/flutter/flutter/issues/5867

The current implementation matches the default behaviour of the material
scaffold.