This adds support for keywords like `return`, `yield`, `break`, `continue` to Document Highlights. For break/continue, the matching loop keyword (`do`/`while`/`for`) is also highlighted (and this works in both directions). This behaviour matches what I see for TypeScript in VS Code.
This is only supported for LSP because the legacy protocol groups these by "Elements" which we don't have for loops (though since IntelliJ uses its own data for occurrences, it's not clear to me if anyone is using Occurrences over the legacy protocol).
Fixes https://github.com/dart-lang/sdk/issues/61170
Change-Id: I5563ec0a91a6fe33d10a6317d33e9256b3c50209
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/442061
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Danny Tuppeny