From 737c34977558cc61be522388a55000c7c2d1d770 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Mon, 13 Oct 2014 05:34:18 +1100
Subject: [PATCH] add util.isReferenced to check if a node is directly
 referenced

---
 lib/6to5/util.js | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/lib/6to5/util.js b/lib/6to5/util.js
index 4e042bc748..b7016ad0d9 100644
--- a/lib/6to5/util.js
+++ b/lib/6to5/util.js
@@ -150,6 +150,24 @@ exports.template = function (name, nodes, keepExpression) {
   }
 };
 
+exports.isReferenced = function (node, parent) {
+  // we're a property key
+  if (parent.type === "Property" && parent.key === node) return false;
+
+  var isMemberExpression = parent.type === "MemberExpression";
+
+  // we're in a member expression and we're the computed property so we're referenced
+  var isComputedProperty = isMemberExpression && parent.property === node && parent.computed;
+
+  // we're in a member expression and we're the object so we're referenced
+  var isObject = isMemberExpression && parent.object === node;
+
+  // we are referenced
+  if (!isMemberExpression || isComputedProperty || isObject) return true;
+
+  return false;
+};
+
 exports.codeFrame = function (lines, lineNumber, colNumber) {
   colNumber = Math.max(colNumber, 0);