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

test/codegen/expect/methods.js

Index: test/codegen/expect/methods.js
diff --git a/test/codegen/expect/methods.js b/test/codegen/expect/methods.js
index 708b0ce457c45f68eb0864161f508121862d41f6..2c47380e70901d31e853ee61e22645c1dd1cc89f 100644
--- a/test/codegen/expect/methods.js
+++ b/test/codegen/expect/methods.js
@@ -4,7 +4,7 @@ var methods;
   let _c = Symbol('_c');
   class A extends core.Object {
     A() {
-      this[_c] = 3;
+      dart.initField(A, this, _c, 3);
     }
     x() {
       return 42;
@@ -48,7 +48,7 @@ var methods;
   }
   class Foo extends core.Object {
     Foo() {
-      this.bar = new Bar();
+      dart.initField(Foo, this, 'bar', new Bar());
     }
   }
   // Function test: () → dynamic