Add --modules=node support

lib/src/codegen/js_codegen.dart

Index: lib/src/codegen/js_codegen.dart
diff --git a/lib/src/codegen/js_codegen.dart b/lib/src/codegen/js_codegen.dart
index 8104a628f51c1dbc5fe6dfcd8ab8ebd0563e8fa0..486eae63471dad8cf9bb8c8bcb62ea8295235ae3 100644
--- a/lib/src/codegen/js_codegen.dart
+++ b/lib/src/codegen/js_codegen.dart
@@ -25,7 +25,7 @@ import '../js/js_ast.dart' as JS;
 import '../js/js_ast.dart' show js;
 
 import '../closure/closure_annotator.dart' show ClosureAnnotator;
-import '../compiler.dart' show AbstractCompiler;
+import '../compiler.dart' show AbstractCompiler, corelibUriOrder;
 import '../info.dart';
 import '../options.dart' show CodegenOptions;
 import '../utils.dart';
@@ -80,7 +80,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
 
   /// Imported libraries, and the temporaries used to refer to them.
   final _imports = new Map<LibraryElement, JS.TemporaryId>();
-  final _exports = new Set<String>();
+  final _exports = <String, String>{};
   final _lazyFields = <VariableDeclaration>[];
   final _properties = <FunctionDeclaration>[];
   final _privateNames = new HashMap<String, JS.TemporaryId>();
@@ -179,16 +179,18 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
       id.setQualified(!_loader.isLoaded(element));
     }
 
-    var moduleBuilder = new ModuleBuilder(
-        compiler.getModuleName(currentLibrary.source.uri),
-        _jsModuleValue,
-        _exportsVar,
-        options.moduleFormat);
-
+    var moduleBuilder = new ModuleBuilder(options.moduleFormat);
     _exports.forEach(moduleBuilder.addExport);
 
     var items = <JS.ModuleItem>[];
     if (!_isDartRuntime) {
+      if (currentLibrary.source.isInSystemLibrary) {
+        // Force the import order of runtime libs.
+        // TODO(ochafik): Reduce this to a minimum.
+        for (var lib in corelibUriOrder.reversed) {
+          moduleBuilder.addImport(lib.replaceAll(':', '/'), null);
+        }
+      }
       moduleBuilder.addImport('dart/_runtime', _runtimeLibVar);
 
       var dartxImport =
@@ -208,7 +210,11 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     // var jsBin = compiler.options.runnerOptions.v8Binary;
     // String scriptTag = null;
     // if (library.library.scriptTag != null) scriptTag = '/usr/bin/env $jsBin';
-    return moduleBuilder.build(items);
+    return moduleBuilder.build(
+        compiler.getModuleName(currentLibrary.source.uri),
+        _jsModuleValue,
+        _exportsVar,
+        items);
   }
 
   void _emitModuleItem(AstNode node) {
@@ -266,8 +272,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
       args.add(new JS.ArrayInitializer(hiddenNames));
     }
 
-    // When we compile _runtime.js, we need to source export_ from _utils.js:
-    _moduleItems.add(js.statement('dart.export(#);', [args]));
+    _moduleItems.add(js.statement('dart.export_(#);', [args]));
   }
 
   JS.Identifier _initSymbol(JS.Identifier id) {
@@ -530,7 +535,8 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     if (genericDef != null) {
       var dynType = fillDynamicTypeArgs(type, types);
       var genericInst = _emitTypeName(dynType, lowerGeneric: true);
-      return js.statement('{ #; let # = #; }', [genericDef, name, genericInst]);
+      return js
+          .statement('{ #; const # = #; }', [genericDef, name, genericInst]);
     }
     return body;
   }
@@ -539,7 +545,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     var name = type.name;
     var genericName = '$name\$';
     var typeParams = _boundTypeParametersOf(type).map((p) => p.name);
-    if (isPublic(name)) _exports.add(genericName);
+    if (isPublic(name)) _addExport(genericName);
     return js.statement('const # = dart.generic(function(#) { #; return #; });',
         [genericName, typeParams, body, name]);
   }
@@ -1285,7 +1291,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     var body = <JS.Statement>[];
     _flushLibraryProperties(body);
 
-    var name = _getJSExportName(node.element) ?? node.name.name;
+    var name = node.name.name;
 
     var fn = _visit(node.functionExpression);
 
@@ -1301,7 +1307,9 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
           .toStatement());
     }
 
-    if (isPublic(name)) _addExport(name);
+    if (isPublic(name)) {
+      _addExport(name, _getJSExportName(node.element) ?? name);
+    }
     return _statement(body);
   }
 
@@ -1735,7 +1743,6 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
 
   JS.Expression _emitTopLevelName(Element e, {String suffix: ''}) {
     var libName = _libraryName(e.library);
-    var nameExpr = _propertyName((_getJSExportName(e) ?? e.name) + suffix);
 
     // Always qualify:
     // * mutable top-level fields
@@ -1744,6 +1751,12 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
         !e.isConst &&
         !_isFinalJSDecl(e.computeNode());
     bool fromAnotherLibrary = e.library != currentLibrary;
+    var nameExpr;
+    if (fromAnotherLibrary) {
+      nameExpr = _propertyName((_getJSExportName(e) ?? e.name) + suffix);
+    } else {
+      nameExpr = _propertyName(e.name + suffix);
+    }
     if (mutableTopLevel || fromAnotherLibrary) {
       return new JS.PropertyAccess(libName, nameExpr);
     }
@@ -2136,8 +2149,10 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     }
   }
 
-  _addExport(String name) {
-    if (!_exports.add(name)) throw 'Duplicate top level name found: $name';
+  _addExport(String name, [String exportName]) {
+    if (_exports.containsKey(name))
+      throw 'Duplicate top level name found: $name';
+    _exports[name] = exportName ?? name;
   }
 
   @override
@@ -2199,8 +2214,9 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
     if (isJSTopLevel) eagerInit = true;
 
     var fieldName = field.name.name;
+    var exportName = fieldName;
     if (element is TopLevelVariableElement) {
-      fieldName = _getJSExportName(element) ?? fieldName;
+      exportName = _getJSExportName(element) ?? fieldName;
     }
     if ((field.isConst && eagerInit && element is TopLevelVariableElement) ||
         isJSTopLevel) {
@@ -2208,7 +2224,7 @@ class JSCodegenVisitor extends GeneralizingAstVisitor with ClosureAnnotator {
       // but add them to the module's exports. However, make sure we generate
       // anything they depend on first.
 
-      if (isPublic(fieldName)) _addExport(fieldName);
+      if (isPublic(fieldName)) _addExport(fieldName, exportName);
       var declKeyword = field.isConst || field.isFinal ? 'const' : 'let';
       return annotateVariable(
           js.statement(