Fix regex detection

Author: wooorm

index.js

@@ -1,6 +1,7 @@
 'use strict';
 
 var array = require('isarray');
+var regexp = require('is-regex');
 var visit = require('unist-util-visit-parents');
 var is = require('hast-util-is-element');
 var escape = require('escape-string-regexp');
@@ -15,7 +16,7 @@ function findAndReplace(tree, find, replace, options) {
   var settings;
   var schema;
 
-  if (typeof find === 'string' || (typeof find === 'object' && 'flags' in find)) {
+  if (typeof find === 'string' || regexp(find)) {
     schema = [[find, replace]];
   } else {
     schema = find;

package.json

@@ -23,6 +23,7 @@
   "dependencies": {
     "escape-string-regexp": "^1.0.5",
     "hast-util-is-element": "^1.0.0",
+    "is-regex": "^1.0.3",
     "isarray": "^2.0.1",
     "unist-util-visit-parents": "^1.1.0"
   },