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

test/codegen/expect/sunflower.js

 var sunflower;
 (function(exports) {
   'use strict';
   let ORANGE = "orange";
   let SEED_RADIUS = 2;
   let SCALE_FACTOR = 4;
   let TAU = dart.notNull(math.PI) * 2;
   let MAX_D = 300;
   let centerX = dart.notNull(MAX_D) / 2;
   let centerY = centerX;
   // Function querySelector: (String) → Element
   function querySelector(selector) {
     return dom.document.querySelector(selector);
   }
   exports.seeds = 0;
   dart.defineLazyProperties(exports, {
     get slider() {
       return dart.as(querySelector("#slider"), dom.InputElement);
     },
     get notes() {
       return querySelector("#notes");
     },
     get PHI() {
       return (dart.notNull(math.sqrt(5)) + 1) / 2;
     },
     get context() {
       return dart.as(dart.as(querySelector("#canvas"), dom.CanvasElement).getContext('2d'), dom.CanvasRenderingContext2D);
     }
   });
-  class Circle extends dart.Object {
+  class Circle extends core.Object {
     Circle(x, y, radius) {
       this.x = x;
       this.y = y;
       this.radius = radius;
     }
   }
-  class CirclePainter extends dart.Object {
+  class CirclePainter extends core.Object {
     CirclePainter() {
       this.color = ORANGE;
     }
     draw() {
       exports.context.beginPath();
       exports.context.lineWidth = 2;
       exports.context.fillStyle = this.color;
       exports.context.strokeStyle = this.color;
       exports.context.arc(this.x, this.y, this.radius, 0, TAU, false);
       exports.context.fill();
@@ skipping 36 matching lines @@
   exports.MAX_D = MAX_D;
   exports.centerX = centerX;
   exports.centerY = centerY;
   exports.querySelector = querySelector;
   exports.Circle = Circle;
   exports.CirclePainter = CirclePainter;
   exports.SunflowerSeed = SunflowerSeed;
   exports.main = main;
   exports.draw = draw;
 })(sunflower || (sunflower = {}));