From 08dde229392aec651434cccc01056fbec49e73ab Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sat, 27 Dec 2014 19:12:56 +1100
Subject: [PATCH] better ClassDeclaration contextual transformation

---
 .../transformation/transformers/es6-classes.js     | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/6to5/transformation/transformers/es6-classes.js b/lib/6to5/transformation/transformers/es6-classes.js
index 383a477d3d..db1022a33d 100644
--- a/lib/6to5/transformation/transformers/es6-classes.js
+++ b/lib/6to5/transformation/transformers/es6-classes.js
@@ -3,7 +3,19 @@ var util     = require("../../util");
 var t        = require("../../types");
 
 exports.ClassDeclaration = function (node, parent, file, scope) {
-  return new Class(node, file, scope, false).run();
+  var closure = true;
+  if (t.isProgram(parent) || t.isBlockStatement(parent)) {
+    closure = false;
+  }
+
+  var newNode = new Class(node, file, scope, closure).run();
+  if (closure || t.isFunctionExpression(newNode)) {
+    return t.variableDeclaration("let", [
+      t.variableDeclarator(node.id, newNode)
+    ]);
+  } else {
+    return newNode;
+  }
 };
 
 exports.ClassExpression = function (node, parent, file, scope) {