Named constants are (usually) not null.

test/codegen/expect/fieldtest.js

 dart_library.library('fieldtest', null, /* Imports */[
   'dart_sdk'
 ], function(exports, dart_sdk) {
   'use strict';
   const core = dart_sdk.core;
   const dart = dart_sdk.dart;
   const dartx = dart_sdk.dartx;
   const fieldtest = Object.create(null);
   fieldtest.A = class A extends core.Object {
     A() {
@@ skipping 77 matching lines @@
       methods: () => ({foo: [dart.dynamic, [T]]})
     });
     return Generic;
   });
   fieldtest.Generic = fieldtest.Generic$();
   fieldtest.Generic.bar = 'hello';
   fieldtest.StaticFieldOrder1 = class StaticFieldOrder1 extends core.Object {};
   fieldtest.StaticFieldOrder1.d = 4;
   dart.defineLazy(fieldtest.StaticFieldOrder1, {
     get a() {
-      return dart.notNull(fieldtest.StaticFieldOrder1.b) + 1;
+      return fieldtest.StaticFieldOrder1.b + 1;
     },
     get c() {
-      return dart.notNull(fieldtest.StaticFieldOrder1.d) + 2;
+      return fieldtest.StaticFieldOrder1.d + 2;
     },
     get b() {
-      return dart.notNull(fieldtest.StaticFieldOrder1.c) + 3;
+      return fieldtest.StaticFieldOrder1.c + 3;
     }
   });
   fieldtest.StaticFieldOrder2 = class StaticFieldOrder2 extends core.Object {};
   fieldtest.StaticFieldOrder2.d = 4;
   dart.defineLazy(fieldtest.StaticFieldOrder2, {
     get a() {
-      return dart.notNull(fieldtest.StaticFieldOrder2.b) + 1;
+      return fieldtest.StaticFieldOrder2.b + 1;
     },
     get c() {
-      return dart.notNull(fieldtest.StaticFieldOrder2.d) + 2;
+      return fieldtest.StaticFieldOrder2.d + 2;
     },
     get b() {
-      return dart.notNull(fieldtest.StaticFieldOrder2.c) + 3;
+      return fieldtest.StaticFieldOrder2.c + 3;
     }
   });
   fieldtest.MyEnum = class MyEnum extends core.Object {
     MyEnum(index) {
       this.index = index;
     }
     toString() {
       return {
         0: "MyEnum.Val1",
         1: "MyEnum.Val2",
@@ skipping 12 matching lines @@
     fieldtest.foo(a);
     fieldtest.bar(a);
     core.print(fieldtest.baz(a));
     core.print(new (fieldtest.Generic$(core.String))().foo(' world'));
     core.print(fieldtest.MyEnum.values);
   };
   dart.fn(fieldtest.main, dart.void, []);
   // Exports:
   exports.fieldtest = fieldtest;
 });