Using FileKind, and creating result objects for non-Dart files

[scheglov]

All analyzer/lib/src/dart/analysis/results.dart are Dart results. But we use ErrorsResultImpl to report errors in non-Dart files, like analysis_options.yaml, pubspec.yaml, etc. Which might very well be a good service for users, but the implementation is wrong. If a higher level tool (like DAS) needs a higher level abstraction of "an arbitrary analyzed file", it should wrap and split Dart analysis results vs. other file analysis results.

[bwilkerson]

While I appreciate what you're saying, all of our user-facing tooling performs analysis on all of the files used in Dart development. If we want to have a parallel set of classes for the analysis of YAML files, that's fine, but it isn't just the analysis server that needs it, we also need this support to be available for plugins.

[scheglov]

Maybe. I think we have some utilities from analyzer_plugin used in analysis_server. So, classes for YAML analysis results could live in analyzer_plugin, or even in analyzer - because we still have analyzer_cli that also analyses YAML files, and also constructs ErrorsResultImpl instances for them. We just should not pretend that these are Dart analysis results.