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

test/codegen/expect/names.js

Index: test/codegen/expect/names.js
diff --git a/test/codegen/expect/names.js b/test/codegen/expect/names.js
index 548fd7ec2dc82f2792cb5e9a2baaf23573c00cee..dde823d6c4f54fcb6d84a22c4eef719ff4c6424d 100644
--- a/test/codegen/expect/names.js
+++ b/test/codegen/expect/names.js
@@ -12,9 +12,13 @@ var names;
   function _foo() {
     return 456;
   }
+  let arguments$ = Symbol('arguments');
   class Frame extends core.Object {
-    ['caller*'](arguments$) {
-      this.arguments = arguments$;
+    get arguments() {
+      return this[arguments$];
+    }
+    ['caller*'](arguments$0) {
+      this[arguments$] = arguments$0;
     }
     static ['callee*']() {
       return null;