Change List constructors.

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

Index: sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
diff --git a/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart b/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
index 752a6723b7510c8f90374fbc8d8e0138925dbb9f..1e5d9d2172607a92cfad1181d237d8b119fb69c7 100644
--- a/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
+++ b/sdk/lib/_internal/compiler/implementation/lib/isolate_patch.dart
@@ -1111,7 +1111,7 @@ class _Copier extends _MessageTraverser {
     int len = list.length;
 
     // TODO(floitsch): we loose the generic type of the List.
-    copy = new List(len);
+    copy = new List.fixedLength(len);
     _visited[list] = copy;
     for (int i = 0; i < len; i++) {
       copy[i] = _dispatch(list[i]);
@@ -1165,7 +1165,7 @@ class _Serializer extends _MessageTraverser {
 
   _serializeList(List list) {
     int len = list.length;
-    var result = new List(len);
+    var result = new List.fixedLength(len);
     for (int i = 0; i < len; i++) {
       result[i] = _dispatch(list[i]);
     }