add types.toComputedPropertyKey helper

lib/6to5/types/index.js

@@ -64,6 +64,21 @@ _.each(t.FLIPPED_ALIAS_KEYS, function (types, type) {
   addAssert(type, is);
 });
 
+/**
+ * Description
+ *
+ * @param {Object} node
+ * @returns {Object}
+ */
+
+t.toComputedPropertyKey = function (prop) {
+  var key = prop.key;
+  if (!prop.computed) {
+    if (t.isIdentifier(key)) key = t.literal(key.name);
+  }
+  return key;
+};
+
 /*
  * Shallowly checks to see if the passed `node` will evaluate to a
  * falsy. This is if `node` is a `Literal` and `value` is falsy or