Add List.insert.

sdk/lib/_collection_dev/list.dart

Index: sdk/lib/_collection_dev/list.dart
diff --git a/sdk/lib/_collection_dev/list.dart b/sdk/lib/_collection_dev/list.dart
index 9685fda673a1ecf8d6ce2203af4342eb4bfce38b..c51bc415ad440bedb225b5094da9beb0046676cc 100644
--- a/sdk/lib/_collection_dev/list.dart
+++ b/sdk/lib/_collection_dev/list.dart
@@ -90,6 +90,11 @@ abstract class FixedLengthListBase<E> extends ListBase<E> {
         "Cannot add to a fixed-length list");
   }
 
+  void insert(int index, E value) {
+    throw new UnsupportedError(
+        "Cannot add to a fixed-length list");
+  }
+
   void addAll(Iterable<E> iterable) {
     throw new UnsupportedError(
         "Cannot add to a fixed-length list");
@@ -171,6 +176,11 @@ abstract class UnmodifiableListBase<E> extends ListBase<E> {
         "Cannot add to an unmodifiable list");
   }
 
+  E insert(int index, E value) {
+    throw new UnsupportedError(
+        "Cannot add to an unmodifiable list");
+  }
+
   void addAll(Iterable<E> iterable) {
     throw new UnsupportedError(
         "Cannot add to an unmodifiable list");