keep mixin and interface implementation info at runtime

lib/src/codegen/js_codegen.dart

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library dev_compiler.src.codegen.js_codegen;
 
 import 'dart:collection' show HashSet, HashMap;
 import 'dart:io' show Directory, File;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
@@ skipping 269 matching lines @@
 
   @override
   JS.Statement visitClassDeclaration(ClassDeclaration node) {
     // If we've already emitted this class, skip it.
     var classElem = node.element;
     if (_pendingClasses.remove(classElem) == null) return null;
     if (_getJsNameAnnotation(node) != null) return null;
 
     currentClass = node;
 
-    var name = classElem.name;
-
     var ctors = <ConstructorDeclaration>[];
     var fields = <FieldDeclaration>[];
     var staticFields = <FieldDeclaration>[];
     for (var member in node.members) {
       if (member is ConstructorDeclaration) {
         ctors.add(member);
       } else if (member is FieldDeclaration) {
         (member.isStatic ? staticFields : fields).add(member);
       }
     }
 
-    var classExpr = new JS.ClassExpression(new JS.Identifier(name),
+    var classExpr = new JS.ClassExpression(new JS.Identifier(classElem.name),
         _classHeritage(node), _emitClassMethods(node, ctors, fields));
 
-    var body = _finishClassMembers(name, classExpr, ctors, staticFields);
+    var body = _finishClassMembers(classElem, classExpr, ctors, staticFields);
     currentClass = null;
 
     return _finishClassDef(classElem, body);
   }
 
   @override
   JS.Statement visitEnumDeclaration(EnumDeclaration node) =>
       _unimplementedCall("Unimplemented enum: $node").toStatement();
 
   /// Given a class element and body, complete the class declaration.
@@ skipping 222 matching lines @@
         };
       }''');
       jsMethods.add(new JS.Method(js.call('$_SYMBOL.iterator'), body));
     }
     return jsMethods.where((m) => m != null).toList(growable: false);
   }
 
   /// Emit class members that need to come after the class declaration, such
   /// as static fields. See [_emitClassMethods] for things that are emitted
   /// insite the ES6 `class { ... }` node.
-  JS.Statement _finishClassMembers(String name, JS.ClassExpression cls,
-      List<ConstructorDeclaration> ctors, List<FieldDeclaration> staticFields) {
+  JS.Statement _finishClassMembers(ClassElement classElem,
+      JS.ClassExpression cls, List<ConstructorDeclaration> ctors,
+      List<FieldDeclaration> staticFields) {
+    var name = classElem.name;
+
     var body = <JS.Statement>[];
     body.add(new JS.ClassDeclaration(cls));
 
+    // Interfaces
+    if (classElem.interfaces.isNotEmpty) {
+      body.add(js.statement('#[dart.implements] = #;', [
+        name,
+        new JS.ArrayInitializer(
+            classElem.interfaces.map(_emitTypeName).toList())
+      ]));
+    }
+
     // Named constructors
     for (ConstructorDeclaration member in ctors) {
       if (member.name != null) {
         body.add(js.statement('dart.defineNamedConstructor(#, #);', [
           name,
           _jsMemberName(member.name.name, isStatic: true)
         ]));
       }
     }
 
     // Static fields
     var lazyStatics = <VariableDeclaration>[];
     for (FieldDeclaration member in staticFields) {
       for (VariableDeclaration field in member.fields.variables) {
         var fieldName = field.name.name;
         if (field.isConst || _isFieldInitConstant(field)) {
           var init = _visit(field.initializer);
           if (init == null) init = new JS.LiteralNull();
           body.add(js.statement('#.# = #;', [name, fieldName, init]));
         } else {
           lazyStatics.add(field);
         }
       }
     }
     var lazy = _emitLazyFields(new JS.Identifier(name), lazyStatics);
     if (lazy != null) body.add(lazy);
+
     return _statement(body);
   }
 
   /// Generates the implicit default constructor for class C of the form
   /// `C() : super() {}`.
   JS.Method _emitImplicitConstructor(
       ClassDeclaration node, String name, List<FieldDeclaration> fields) {
     // If we don't have a method body, skip this.
     if (fields.isEmpty) return null;
 
@@ skipping 1763 matching lines @@
 
     // TODO(jmesserly): in many cases marking the end will be unncessary.
     printer.mark(_location(node.end));
   }
 
   String _getIdentifier(AstNode node) {
     if (node is SimpleIdentifier) return node.name;
     return null;
   }
 }