Fix try catch crasher bug due to null else case.

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 1731 matching lines @@
     if (node.parent is ExpressionStatement) {
       return js.statement('throw #;', _visit(_catchParameter));
     } else {
       return js.call('dart.throw_(#)', _visit(_catchParameter));
     }
   }
 
   @override
   JS.If visitIfStatement(IfStatement node) {
     return new JS.If(_visit(node.condition), _visit(node.thenStatement),
-        _visitOrEmpty(node.elseStatement));
+        _visit(node.elseStatement));
   }
 
   @override
   JS.For visitForStatement(ForStatement node) {
     var init = _visit(node.initialization);
     if (init == null) init = _visit(node.variables);
     return new JS.For(init, _visit(node.condition),
         _visitListToBinary(node.updaters, ','), _visit(node.body));
   }
 
@@ skipping 566 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;
   }
 }