Add --modules=node support

test/codegen/expect/collection/src/canonicalized_map.js

Index: test/codegen/expect/collection/src/canonicalized_map.js
diff --git a/test/codegen/expect/collection/src/canonicalized_map.js b/test/codegen/expect/collection/src/canonicalized_map.js
index 03744bc169ca52cb1f9dae9898e42e2c3e091135..3e1e9ab14bfea214dd4a444f1b1d725e8bc8cd82 100644
--- a/test/codegen/expect/collection/src/canonicalized_map.js
+++ b/test/codegen/expect/collection/src/canonicalized_map.js
@@ -32,12 +32,9 @@ dart_library.library('collection/src/canonicalized_map', null, /* Imports */[
         return pair == null ? null : pair.last;
       }
       set(key, value) {
-        (() => {
-          dart.as(key, K);
-          dart.as(value, V);
-          if (!dart.notNull(this[_isValidKey](key))) return;
-          this[_base].set(dart.as(dart.dcall(this[_canonicalize], key), C), new (utils.Pair$(K, V))(key, value));
-        })();
+        dart.as(key, K);
+        dart.as(value, V);
+        this[_base].set(dart.as(dart.dcall(this[_canonicalize], key), C), new (utils.Pair$(K, V))(key, value));
         return value;
       }
       addAll(other) {
@@ -65,7 +62,7 @@ dart_library.library('collection/src/canonicalized_map', null, /* Imports */[
         return this[_base].isNotEmpty;
       }
       get keys() {
-        return this[_base].values[dartx.map](dart.fn(pair => pair.first, K, [utils.Pair$(K, V)]));
+        return dart.as(this[_base].values[dartx.map](dart.fn(pair => pair.first, K, [utils.Pair$(K, V)])), core.Iterable$(K));
       }
       get length() {
         return this[_base].length;
@@ -81,7 +78,7 @@ dart_library.library('collection/src/canonicalized_map', null, /* Imports */[
         return pair == null ? null : pair.last;
       }
       get values() {
-        return this[_base].values[dartx.map](dart.fn(pair => pair.last, V, [utils.Pair$(K, V)]));
+        return dart.as(this[_base].values[dartx.map](dart.fn(pair => pair.last, V, [utils.Pair$(K, V)])), core.Iterable$(V));
       }
       toString() {
         return collection.Maps.mapToString(this);