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

test/codegen/expect/constructors.js

 var constructors;
 (function(exports) {
   'use strict';
-  class A extends dart.Object {
+  class A extends core.Object {
   }
-  class B extends dart.Object {
+  class B extends core.Object {
     B() {
     }
   }
-  class C extends dart.Object {
+  class C extends core.Object {
     C$named() {
     }
   }
   dart.defineNamedConstructor(C, 'named');
   class C2 extends C {
     C2$named() {
       super.C$named();
     }
   }
   dart.defineNamedConstructor(C2, 'named');
-  class D extends dart.Object {
+  class D extends core.Object {
     D() {
     }
     D$named() {
     }
   }
   dart.defineNamedConstructor(D, 'named');
-  class E extends dart.Object {
+  class E extends core.Object {
     E(name) {
       this.name = name;
     }
   }
   class F extends E {
     F(name) {
       super.E(name);
     }
   }
-  class G extends dart.Object {
+  class G extends core.Object {
     G(p1) {
       if (p1 === void 0)
         p1 = null;
     }
   }
-  class H extends dart.Object {
+  class H extends core.Object {
     H(opt$) {
       let p1 = opt$.p1 === void 0 ? null : opt$.p1;
     }
   }
-  class I extends dart.Object {
+  class I extends core.Object {
     I() {
       this.name = 'default';
     }
     I$named(name) {
       this.name = name;
     }
   }
   dart.defineNamedConstructor(I, 'named');
-  class J extends dart.Object {
+  class J extends core.Object {
     J() {
       this.initialized = true;
       this.nonInitialized = null;
     }
   }
-  class K extends dart.Object {
+  class K extends core.Object {
     K() {
       this.s = 'a';
     }
     K$withS(s) {
       this.s = s;
     }
   }
   dart.defineNamedConstructor(K, 'withS');
-  class L extends dart.Object {
+  class L extends core.Object {
     L(foo) {
       this.foo = foo;
     }
   }
   class M extends L {
     M$named(x) {
       super.L(dart.notNull(x) + 42);
     }
   }
   dart.defineNamedConstructor(M, 'named');
@@ skipping 27 matching lines @@
   exports.G = G;
   exports.H = H;
   exports.I = I;
   exports.J = J;
   exports.K = K;
   exports.L = L;
   exports.M = M;
   exports.N = N;
   exports.P = P;
 })(constructors || (constructors = {}));