dart2js cps: Support sync* and yield.

pkg/compiler/lib/src/js_backend/codegen/codegen.dart

 // Copyright (c) 2014, 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 code_generator;
 
 import 'glue.dart';
 
 import '../../closure.dart' show ClosureClassElement;
 import '../../common/codegen.dart' show CodegenRegistry;
@@ skipping 820 matching lines @@
   js.Expression visitForeignExpression(tree_ir.ForeignExpression node) {
     return handleForeignCode(node);
   }
 
   @override
   void visitForeignStatement(tree_ir.ForeignStatement node) {
     accumulator.add(handleForeignCode(node));
   }
 
   @override
+  void visitYield(tree_ir.Yield node) {
+    js.Expression value = visitExpression(node.input);
+    accumulator.add(new js.DartYield(value, node.hasStar));
+  }
+
+  @override
   js.Expression visitApplyBuiltinOperator(tree_ir.ApplyBuiltinOperator node) {
     List<js.Expression> args = visitExpressionList(node.arguments);
     switch (node.operator) {
       case BuiltinOperator.NumAdd:
         return new js.Binary('+', args[0], args[1]);
       case BuiltinOperator.NumSubtract:
         return new js.Binary('-', args[0], args[1]);
       case BuiltinOperator.NumMultiply:
         return new js.Binary('*', args[0], args[1]);
       case BuiltinOperator.NumAnd:
@@ skipping 58 matching lines @@
   js.Expression visitAwait(tree_ir.Await node) {
     return new js.Await(visitExpression(node.input));
   }
 
   visitFunctionExpression(tree_ir.FunctionExpression node) {
     // FunctionExpressions are currently unused.
     // We might need them if we want to emit raw JS nested functions.
     throw 'FunctionExpressions should not be used';
   }
 }