js: fix core.Object, output order, static const fields

test/codegen/expect/BenchmarkBase.js

 var BenchmarkBase;
 (function(exports) {
   'use strict';
-  class Expect extends dart.Object {
+  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.length !== actual.length) {
         throw `Lists have different lengths: ${expected.length} vs ${actual.length}`;
       }
       for (let i = 0; dart.notNull(i) < dart.notNull(actual.length); i = dart.notNull(i) + 1) {
         equals(expected.get(i), actual.get(i));
       }
     }
     fail(message) {
       throw message;
     }
   }
-  class BenchmarkBase extends dart.Object {
+  class BenchmarkBase extends core.Object {
     BenchmarkBase(name) {
       this.name = name;
     }
     run() {}
     warmup() {
       this.run();
     }
     exercise() {
       for (let i = 0; dart.notNull(i) < 10; i = dart.notNull(i) + 1) {
         this.run();
@@ skipping 27 matching lines @@
     }
     report() {
       let score = this.measure();
       core.print(`${this.name}(RunTime): ${score} us.`);
     }
   }
   // Exports:
   exports.Expect = Expect;
   exports.BenchmarkBase = BenchmarkBase;
 })(BenchmarkBase || (BenchmarkBase = {}));