Add "last" setter to List.

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 c93a3d7470b56dec5a69372c02a2ffe4142ec34e..14662caf7fd590ffae02fe13e28985376b6ba775 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -34932,7 +34932,11 @@ abstract class ImmutableListMixin<E> implements List<E> {
     return new FixedSizeListIterator<E>(this);
   }
 
-  // From Collection<E>:
+  // From List<E>:
+  void set last(E value) {
+    throw new UnsupportedError("Cannot modify an immutable List.");
+  }
+
   void add(E value) {
     throw new UnsupportedError("Cannot add to immutable List.");
   }
@@ -34941,7 +34945,6 @@ abstract class ImmutableListMixin<E> implements List<E> {
     throw new UnsupportedError("Cannot add to immutable List.");
   }
 
-  // From List<E>:
   void sort([int compare(E a, E b)]) {
     throw new UnsupportedError("Cannot sort immutable List.");
   }