Change List constructors.

sdk/lib/_internal/compiler/implementation/lib/js_helper.dart

Index: sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
index 5b4f36a612dd73f37a56a7c035d18e5b31ec40dd..efcc42008406c0588e2bfd3cb7aad2fb37c26127 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/js_helper.dart
@@ -522,11 +522,11 @@ class Primitives {
     return "Instance of '$name'";
   }
 
-  static List newList(length) {
-    if (length == null) return JS('Object', r'new Array()');
-    if ((length is !int) || (length < 0)) {
-      throw new ArgumentError(length);
-    }
+  static List newGrowableList(length) {
+    return JS('Object', r'new Array(#)', length);
+  }
+
+  static List newFixedList(length) {
     var result = JS('Object', r'new Array(#)', length);
     JS('void', r'#.fixed$length = #', result, true);
     return result;