Report invalid, nested, multi-segment crate-paths

Specifically, things like:

use foo::{crate::bar};

Are now being caught, when before we only caught:

use foo::{crate};

1 files changed, 1 insertions, 1 deletions

diff --git a/crates/ra_parser/src/grammar/items/use_item.rs b/crates/ra_parser/src/grammar/items/use_item.rs
index e3b991c8c..3a0c7a31a 100644
--- a/crates/ra_parser/src/grammar/items/use_item.rs
+++ b/crates/ra_parser/src/grammar/items/use_item.rs
@@ -47,7 +47,7 @@ fn use_tree(p: &mut Parser, top_level: bool) {
         // use {crate::path::from::root, or::path::from::crate_name}; // Rust 2018 (with a crate named `or`)
         // use {path::from::root}; // Rust 2015
         // use ::{some::arbritrary::path}; // Rust 2015
-        // use ::{{{crate::export}}}; // Nonsensical but perfectly legal nestnig
+        // use ::{{{root::export}}}; // Nonsensical but perfectly legal nesting
         T!['{'] => {
             use_tree_list(p);
         }