fixes #516, nested cascade code generation

test/codegen/language/cascade_nested_test.dart

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
-// Tests that a super call to access a field in a super class is just a normal
-// field access.
-
 import "package:expect/expect.dart";
 
-class A {
+class Foo {
+  int x;
+}
+
+class Bar {
+  Foo foo;
   int y;
 }
 
-class B extends A {
-  int get x => super.y;
-  void set x(val) { super.y = val; }
+main() {
+  var bar = new Bar()
+    ..foo = (new Foo()..x = 42)
+    ..y = 38;
+  Expect.isTrue(bar is Bar);
+  Expect.isTrue(bar.foo is Foo);
+  Expect.equals(bar.foo.x, 42);
+  Expect.equals(bar.y, 38);
 }
-
-void main() {
-  var b = new B();
-  b.x = 42;
-  Expect.equals(42, b.x);
-}