fix temp used in postfix ops

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 1502 matching lines @@
 
     // Increment and write
     var one = AstBuilder.integerLiteral(1);
     one.staticType = rules.provider.intType;
     var increment = AstBuilder.binaryExpression(tmp, op.lexeme[0], one);
     increment.staticType = type;
     var write = _emitAssignment(expr, increment);
 
     var bindThis = _maybeBindThis(expr);
     return js.call("((#) => (#, #))$bindThis(#)", [
-      tmp.name,
+      _visit(tmp),
       write,
       _visit(tmp),
       _visit(expr)
     ]);
   }
 
   @override
   JS.Expression visitPostfixExpression(PostfixExpression node) {
     var op = node.operator;
     var expr = node.operand;
@@ skipping 795 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;
   }
 }