Implementation Issue for SuperMixins: Intellij

[JekCharlsonYu]

What: Issue for implementation for intellij

ETA: 10/15 in Dart Repo.

For: SuperMixins Implementation and strawman documentation

Meta Issue: This is subsumed under the Super Mixins Meta Issue in the Language Repo

Comments: Feel free to break this further into further tasks and issues, or use as a meta issue for all the tasks in the implementation plan

[devoncarew]

also, cc @alexander-doroshko

[devoncarew]

Note that this will be a syntax change, and updating IntelliJ's parser may block rolling the new mixins into Flutter.

[leafpetersen]

Per @jwren this is at least close to implemented, but we need to make sure it gets rolled into the appropriate versions and released.

[jwren]

@alexander-doroshko implemented in IntelliJ, version IntelliJ IDEA 2018.2.3. @leafpetersen, @bwilkerson and myself just verified.

Dart Plugin version 182.4323.44