delegate removal of nodes in traversal to exitNode

lib/6to5/traverse/index.js

@@ -76,11 +76,6 @@ TraversalContext.prototype.enterNode = function (obj, key, node, enter, parent,
     }
   }
 
-  if (this.shouldRemove) {
-    obj[key] = null;
-    this.shouldFlatten = true;
-  }
-
   return node;
 };
 
@@ -97,6 +92,11 @@ TraversalContext.prototype.exitNode = function (obj, key, node, exit, parent, sc
     }
   }
 
+  if (this.shouldRemove) {
+    obj[key] = null;
+    this.shouldFlatten = true;
+  }
+
   return node;
 };