Add a test for BTreeMap lifetime bound to see if it compiles

src/test/ui/btreemap/btreemap_into_iterator_lifetime.rs

@@ -0,0 +1,23 @@
+// check-pass
+
+use std::collections::{BTreeMap, HashMap};
+
+trait Map
+where
+    for<'a> &'a Self: IntoIterator<Item = (&'a Self::Key, &'a Self::Value)>,
+{
+    type Key;
+    type Value;
+}
+
+impl<K, V> Map for HashMap<K, V> {
+    type Key = K;
+    type Value = V;
+}
+
+impl<K, V> Map for BTreeMap<K, V> {
+  type Key = K;
+  type Value = V;
+}
+
+fn main() {}