Revert "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 f0e914020f31db9b5a8e1ce8427439fcf626b4db..839930e1bf99a4e8babc38e72d632133991efdef 100644
--- a/sdk/lib/html/dartium/html_dartium.dart
+++ b/sdk/lib/html/dartium/html_dartium.dart
@@ -34814,11 +34814,7 @@ abstract class ImmutableListMixin<E> implements List<E> {
     return new FixedSizeListIterator<E>(this);
   }
 
-  // From List<E>:
-  void set last(E value) {
-    throw new UnsupportedError("Cannot modify an immutable List.");
-  }
-
+  // From Collection<E>:
   void add(E value) {
     throw new UnsupportedError("Cannot add to immutable List.");
   }
@@ -34827,6 +34823,7 @@ 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.");
   }