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

test/codegen/expect/BenchmarkBase.js

 var BenchmarkBase;
 (function(exports) {
   'use strict';
   class Expect extends core.Object {
     static equals(expected, actual) {
       if (!dart.equals(expected, actual)) {
         throw `Values not equal: ${expected} vs ${actual}`;
       }
     }
     static listEquals(expected, actual) {
       if (expected[core.$length] != actual[core.$length]) {
         throw `Lists have different lengths: ${expected[core.$length]} vs ${actual[core.$length]}`;
       }
       for (let i = 0; dart.notNull(i) < dart.notNull(actual[core.$length]); i = dart.notNull(i) + 1) {
         Expect.equals(expected[core.$get](i), actual[core.$get](i));
       }
     }
     fail(message) {
       throw message;
     }
   }
+  let name$ = Symbol('name');
   class BenchmarkBase extends core.Object {
+    get name() {
+      return this[name$];
+    }
     BenchmarkBase(name) {
-      this.name = name;
+      this[name$] = name;
     }
     run() {}
     warmup() {
       this.run();
     }
     exercise() {
       for (let i = 0; dart.notNull(i) < 10; i = dart.notNull(i) + 1) {
         this.run();
       }
     }
@@ skipping 25 matching lines @@
     }
     report() {
       let score = this.measure();
       core.print(`${this.name}(RunTime): ${score} us.`);
     }
   }
   // Exports:
   exports.Expect = Expect;
   exports.BenchmarkBase = BenchmarkBase;
 })(BenchmarkBase || (BenchmarkBase = {}));