[Dot Shorthands] Evaluate support for lint `omit_obvious_local_variable_types` and `omit_obvious_property_types`.

[kallentu]

This issue tracks the work needed for these lints to support dot shorthands.

Work needed

• Make sure we aren't suggesting to remove any type that a dot shorthand needs for inference.
• Tests

[eernstg]

A dot shorthand should never be considered to have an obvious type, and I just confirmed that this is also the actual behavior of the lint. So omit_obvious_local_variable_types should not need any updates in order to handle dot shorthands correctly.

https://dart-review.googlesource.com/c/sdk/+/434660 tests this for omit_obvious_local_variable_types as well as omit_obvious_property_types.

[kallentu]

A dot shorthand should never be considered to have an obvious type, and I just confirmed that this is also the actual behavior of the lint. So omit_obvious_local_variable_types should not need any updates in order to handle dot shorthands correctly.

https://dart-review.googlesource.com/c/sdk/+/434660 tests this for omit_obvious_local_variable_types as well as omit_obvious_property_types.

Oh yeah, I had tests up in this CL that I was going to send today: https://dart-review.googlesource.com/c/sdk/+/434541. I think it can be merged into this one.