frontend: Add IntoIterator and Iterator traits to prelude

dora-frontend/src/stdlib_lookup.rs

@@ -117,14 +117,16 @@ pub fn setup_prelude(sa: &mut Sema) {
         "std::unreachable",
         "std::assert",
         "std::primitives::Result",
+        "std::traits::IntoIterator",
+        "std::traits::Iterator",
     ];
 
     let mut prelude_table = SymTable::new();
 
     for name in &symbols {
         let sym = resolve_path(sa, name);
         let name = final_path_name(sa, name);
-        let old_sym = prelude_table.insert(name, sym);
+        let old_sym = prelude_table.insert_use(name, Visibility::Module, sym);
         assert!(old_sym.is_none());
     }
 

tests/stdlib/iterator-count1.dora

@@ -0,0 +1,9 @@
+//= ignore
+
+use std::traits::IntoIterator;
+use std::traits::Iterator;
+
+fn main() {
+    let x = Vec[Int]::new(1, 2, 3, 4, 5);
+    assert(x.iter().count() == 5);
+}