"Go to Type Definition" on closure parameters not working

[FMorschel]

Take the following code:

void foo(List<int> list) {
  list.map((e) => e);
}

If you ask for "Go to Type Declaration" on the last e, you get redirected to the declaration for int, but if you go to the first, you get a message telling you "No type definition found for 'e'":

I volunteer to fix this.

---

CC: @DanTup

[dart-github-bot]

Summary: The "Go to Type Definition" feature doesn't work correctly for closure parameters. When invoked on the second e in the example, it redirects to int, but on the first e, it reports no type definition found.

[scheglov]

It looks that we support VariableDeclaration, but not FormalParameter.

[FMorschel]

https://dart-review.googlesource.com/c/sdk/+/388660