Remove addLast from List.

tools/dom/templates/immutable_list_mixin.darttemplate

Index: tools/dom/templates/immutable_list_mixin.darttemplate
diff --git a/tools/dom/templates/immutable_list_mixin.darttemplate b/tools/dom/templates/immutable_list_mixin.darttemplate
index 11aed324df9b08185954f5a03f19aaafa533cd23..d238fcaab12a1bd45c7305c30dd880607f209b4b 100644
--- a/tools/dom/templates/immutable_list_mixin.darttemplate
+++ b/tools/dom/templates/immutable_list_mixin.darttemplate
@@ -83,10 +83,6 @@ $endif
     throw new UnsupportedError("Cannot add to immutable List.");
   }
 
-  void addLast($E value) {
-    throw new UnsupportedError("Cannot add to immutable List.");
-  }
-
   void addAll(Iterable<$E> iterable) {
     throw new UnsupportedError("Cannot add to immutable List.");
   }