dart2dart: Implementation of simple try/catch.

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 '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../js/js.dart' as js;
@@ skipping 457 matching lines @@
     accumulator.add(
         buildWhile(new js.LiteralBool(true), node.body, node.label, node));
   }
 
   @override
   void visitReturn(tree_ir.Return node) {
     accumulator.add(new js.Return(visitExpression(node.value)));
   }
 
   @override
+  void visitTry(tree_ir.Try node) {
+    // TODO(kmillikin): implement TryStatement.
+    return giveup(node);
+  }
+
+  @override
   js.Expression visitCreateBox(tree_ir.CreateBox node) {
     return new js.ObjectInitializer([]);
   }
 
   @override
   js.Expression visitCreateInstance(tree_ir.CreateInstance node) {
     registry.registerInstantiatedClass(node.classElement);
     return new js.New(glue.constructorAccess(node.classElement),
                       node.arguments.map(visitExpression).toList());
   }
@@ skipping 35 matching lines @@
 
   @override
   visitSuperInitializer(tree_ir.SuperInitializer node) {
     return errorUnsupportedNode(node);
   }
 
   dynamic errorUnsupportedNode(tree_ir.DartSpecificNode node) {
     throw "Unsupported node in JS backend: $node";
   }
 }