Implement modular compilation

test/codegen/expect/names.js

 dart_library.library('names', null, /* Imports */[
-  'dart/_runtime',
-  'dart/core'
-], /* Lazy imports */[
-], function(exports, dart, core) {
+  'dart_sdk'
+], function(exports, dart_sdk) {
   'use strict';
-  let dartx = dart.dartx;
-  exports.exports = 42;
-  const _foo$ = Symbol('_foo');
-  class Foo extends core.Object {
-    [_foo$]() {
+  const core = dart_sdk.core;
+  const dart = dart_sdk.dart;
+  const dartx = dart_sdk.dartx;
+  const names = Object.create(null);
+  names.exports = 42;
+  const _foo = Symbol('_foo');
+  names.Foo = class Foo extends core.Object {
+    [_foo]() {
       return 123;
     }
-  }
-  dart.setSignature(Foo, {
-    methods: () => ({[_foo$]: [dart.dynamic, []]})
+  };
+  dart.setSignature(names.Foo, {
+    methods: () => ({[_foo]: [dart.dynamic, []]})
   });
-  function _foo() {
+  names._foo = function() {
     return 456;
-  }
-  dart.fn(_foo);
-  class Frame extends core.Object {
+  };
+  dart.fn(names._foo);
+  names.Frame = class Frame extends core.Object {
     caller(arguments$) {
       this.arguments = arguments$;
     }
     static callee() {
       return null;
     }
-  }
-  dart.defineNamedConstructor(Frame, 'caller');
-  dart.setSignature(Frame, {
-    constructors: () => ({caller: [Frame, [core.List]]}),
+  };
+  dart.defineNamedConstructor(names.Frame, 'caller');
+  dart.setSignature(names.Frame, {
+    constructors: () => ({caller: [names.Frame, [core.List]]}),
     statics: () => ({callee: [dart.dynamic, []]}),
     names: ['callee']
   });
-  class Frame2 extends core.Object {}
-  dart.defineLazyProperties(Frame2, {
+  names.Frame2 = class Frame2 extends core.Object {};
+  dart.defineLazy(names.Frame2, {
     get caller() {
       return 100;
     },
     set caller(_) {},
     get arguments() {
       return 200;
     },
     set arguments(_) {}
   });
-  function main() {
-    core.print(exports.exports);
-    core.print(new Foo()[_foo$]());
-    core.print(_foo());
-    core.print(new Frame.caller(dart.list([1, 2, 3], core.int)));
-    let eval$ = Frame.callee;
+  names.main = function() {
+    core.print(names.exports);
+    core.print(new names.Foo()[_foo]());
+    core.print(names._foo());
+    core.print(new names.Frame.caller(dart.list([1, 2, 3], core.int)));
+    let eval$ = names.Frame.callee;
     core.print(eval$);
-    core.print(dart.notNull(Frame2.caller) + dart.notNull(Frame2.arguments));
-  }
-  dart.fn(main);
+    core.print(dart.notNull(names.Frame2.caller) + dart.notNull(names.Frame2.arguments));
+  };
+  dart.fn(names.main);
   // Exports:
-  exports.Foo = Foo;
-  exports.Frame = Frame;
-  exports.Frame2 = Frame2;
-  exports.main = main;
+  exports.names = names;
 });