fix resolveRelUrl: don't try to create a rewriting parser from about:…

…blank (and other disallowed prefixes)

default to window.document if passed in document does not have a valid URL (eg. about:blank)
specifically check for https:// or http://
fixes #139

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@webrecorder/wombat",
-  "version": "3.7.2",
+  "version": "3.7.3",
   "main": "index.js",
   "license": "AGPL-3.0-or-later",
   "author": "Ilya Kreymer, Webrecorder Software",

src/wombat.js

@@ -928,7 +928,10 @@ Wombat.prototype.getFinalUrl = function(useRel, mod, url) {
  * @return {string}
  */
 Wombat.prototype.resolveRelUrl = function(url, doc) {
-  var docObj = doc || this.$wbwindow.document;
+  var docObj = this.$wbwindow.document;
+  if (doc && doc.baseURI && (doc.startsWith(HTTPS_PREFIX) || doc.startsWith(HTTP_PREFIX))) {
+    docObj = doc;
+  }
   var parser = this.makeParser(docObj.baseURI, docObj);
 
   return new this.URL(url, parser).href;