Implement typed array constructors.

client/dom/generated/src/frog/HTMLCollection.dart

 
 class HTMLCollection native "HTMLCollection" {
 
   int length;
 
   Node operator[](int index) native;
 
+  void operator[]=(int index, Node value) {
+    throw new UnsupportedOperationException("Cannot assign element of immutable List.");
+  }
+
   Node item(int index) native;
 
   Node namedItem(String name) native;
 
   var dartObjectLocalStorage;
 
   String get typeName() native;
 }