refactor browser/node module load structure

gulpfile.js

@@ -74,7 +74,7 @@ gulp.task('build/zone.js.d.ts', ['compile-esm'], function() {
 
 // Zone for Node.js environment.
 gulp.task('build/zone-node.js', ['compile-esm'], function(cb) {
-  return generateScript('./lib/node/node.ts', 'zone-node.js', false, cb);
+  return generateScript('./lib/node/rollup-main.ts', 'zone-node.js', false, cb);
 });
 
 // Zone for the browser.

lib/browser/browser.ts

@@ -6,8 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import '../common/to-string';
-
 import {patchTimer} from '../common/timers';
 import {findEventTask, patchClass, patchEventTargetMethods, patchMethod, patchPrototype, zoneSymbol} from '../common/utils';
 

lib/browser/rollup-main.ts

@@ -6,7 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-
 import '../zone';
 import '../common/promise';
+import '../common/to-string';
 import './browser';

lib/mix/rollup-mix.ts

@@ -6,7 +6,8 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-
 import '../zone';
+import '../common/promise';
+import '../common/to-string';
 import '../browser/browser';
 import '../node/node';

lib/node/node.ts

@@ -6,9 +6,6 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
-import '../zone';
-import '../common/promise';
-import '../common/to-string';
 import './events';
 import './fs';
 

lib/node/rollup-main.ts

@@ -0,0 +1,12 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import '../zone';
+import '../common/promise';
+import '../common/to-string';
+import './node';

test/browser-zone-setup.ts

@@ -6,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 
+import '../lib/common/to-string';
 import '../lib/browser/browser';
 import '../lib/zone-spec/async-test';
 import '../lib/zone-spec/fake-async-test';

test/node_entry_point.ts

@@ -12,6 +12,8 @@ import './custom_error';
 
 // Setup tests for Zone without microtask support
 import '../lib/zone';
+import '../lib/common/promise';
+import '../lib/common/to-string';
 import '../lib/node/node';
 import '../lib/zone-spec/async-test';
 import '../lib/zone-spec/fake-async-test';