Make "Navigate Class/Symbol" works with items expanded from macros

[vlad20012]

Note that looks like I already enabled search for items expanded from macros in the case of "All places" scope in #4275. But this PR enables it correctly for all scopes (e.g. project/library files)

[artemmukhin]

bors r+

[bors]

Build succeeded

• continuous-integration/travis-ci/push
• continuous-integration/appveyor/branch

[lancelote]

Hm, I was sure I did comment on this 🤔 Anyway, @vlad20012 is goto declaration expected to work in the following case:

macro_rules! foo {
    () => {
        struct FooBarBaz;
    };
}

fn main() {
    foo!();
}

Or is it too much?

[vlad20012]

@lancelote too much :)
Macros inside function bodies are not indexed. In theory, we can simply enable it, but I expect a significant performance regression in this case.