Change List constructors.

sdk/lib/html/dartium/html_dartium.dart

Index: sdk/lib/html/dartium/html_dartium.dart
diff --git a/sdk/lib/html/dartium/html_dartium.dart b/sdk/lib/html/dartium/html_dartium.dart
index 20bdad94b21d032146e776671acfbf57fc953a22..66bf24b43bc4e1614e3f704d5f09eb68da02c84a 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -31510,7 +31510,7 @@ 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]);
@@ -31564,7 +31564,7 @@ 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]);
     }
@@ -31839,7 +31839,7 @@ class _Utils {
   static List convertToList(List list) {
     // FIXME: [possible optimization]: do not copy the array if Dart_IsArray is fine w/ it.
     final length = list.length;
-    List result = new List(length);
+    List result = new List.fixedLength(length);
     result.setRange(0, length, list);
     return result;
   }