fixes #52, fields shadowing getters/setters or other fields

test/codegen/expect/cascade.js

Index: test/codegen/expect/cascade.js
diff --git a/test/codegen/expect/cascade.js b/test/codegen/expect/cascade.js
index 97bdf1eefb46de54e114d384f6a4fbbb9d2497aa..0a890666b8186da66f62fa5315f5d973d433b75a 100644
--- a/test/codegen/expect/cascade.js
+++ b/test/codegen/expect/cascade.js
@@ -3,7 +3,7 @@ var cascade;
   'use strict';
   class A extends core.Object {
     A() {
-      this.x = null;
+      dart.initField(A, this, 'x', null);
     }
   }
   // Function test_closure_with_mutate: () → void
@@ -85,7 +85,7 @@ var cascade;
   let Base$ = dart.generic(function(T) {
     class Base extends core.Object {
       Base() {
-        this.x = new core.List$(T).from([]);
+        dart.initField(Base, this, 'x', new core.List$(T).from([]));
       }
     }
     return Base;