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

test/codegen/expect/dom.js

 var dom;
 (function(exports) {
   'use strict';
-  class JsType extends dart.Object {
+  class JsType extends core.Object {
     JsType(opt$) {
       let name = opt$.name === void 0 ? null : opt$.name;
       this.name = name;
     }
   }
-  class JsGlobal extends dart.Object {
+  class JsGlobal extends core.Object {
     JsGlobal() {
     }
   }
-  class Overload extends dart.Object {
+  class Overload extends core.Object {
     Overload() {
     }
   }
   let overload = new Overload();
   exports.document = null;
-  class Document extends dart.Object {
+  class Document extends core.Object {
   }
-  class Element extends dart.Object {
+  class Element extends core.Object {
     Element() {
       this.textContent = null;
     }
   }
-  class Event extends dart.Object {
+  class Event extends core.Object {
   }
   class InputElement extends Element {
     InputElement() {
       this.value = null;
       super.Element();
     }
   }
   class CanvasElement extends Element {
   }
-  class RenderingContext extends dart.Object {
+  class RenderingContext extends core.Object {
   }
-  class CanvasRenderingContext2D extends dart.Object {
+  class CanvasRenderingContext2D extends core.Object {
     CanvasRenderingContext2D() {
       this.globalAlpha = null;
       this.globalCompositeOperation = null;
       this.strokeStyle = null;
       this.fillStyle = null;
       this.shadowOffsetX = null;
       this.shadowOffsetY = null;
       this.shadowBlur = null;
       this.shadowColor = null;
     }
   }
-  class CanvasDrawingStyles extends dart.Object {
+  class CanvasDrawingStyles extends core.Object {
     CanvasDrawingStyles() {
       this.lineWidth = null;
       this.lineCap = null;
       this.lineJoin = null;
       this.miterLimit = null;
       this.lineDashOffset = null;
       this.font = null;
       this.textAlign = null;
       this.textBaseline = null;
     }
   }
-  class CanvasPathMethods extends dart.Object {
+  class CanvasPathMethods extends core.Object {
   }
-  class CanvasGradient extends dart.Object {
+  class CanvasGradient extends core.Object {
   }
-  class CanvasPattern extends dart.Object {
+  class CanvasPattern extends core.Object {
   }
-  class TextMetrics extends dart.Object {
+  class TextMetrics extends core.Object {
   }
-  class ImageData extends dart.Object {
+  class ImageData extends core.Object {
   }
   // Exports:
   exports.JsType = JsType;
   exports.JsGlobal = JsGlobal;
   exports.Overload = Overload;
   exports.overload = overload;
   exports.Document = Document;
   exports.Element = Element;
   exports.Event = Event;
   exports.InputElement = InputElement;
   exports.CanvasElement = CanvasElement;
   exports.RenderingContext = RenderingContext;
   exports.CanvasRenderingContext2D = CanvasRenderingContext2D;
   exports.CanvasDrawingStyles = CanvasDrawingStyles;
   exports.CanvasPathMethods = CanvasPathMethods;
   exports.CanvasGradient = CanvasGradient;
   exports.CanvasPattern = CanvasPattern;
   exports.TextMetrics = TextMetrics;
   exports.ImageData = ImageData;
 })(dom || (dom = {}));