Issue 5300 - Add feature detection for object_subrequest

lib/requestBlocker.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2017 eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 11 matching lines @@
 const {Filter, RegExpFilter, BlockingFilter} = require("filterClasses");
 const {Subscription} = require("subscriptionClasses");
 const {defaultMatcher} = require("matcher");
 const {FilterNotifier} = require("filterNotifier");
 const {Prefs} = require("prefs");
 const {checkWhitelisted, getKey} = require("whitelisting");
 const {stringifyURL, extractHostFromFrame, isThirdParty} = require("url");
 const {port} = require("messaging");
 const devtools = require("devtools");
 
-// Chrome and Firefox (WebExtensions) can't distinguish between
-// OBJECT_SUBREQUEST and OBJECT requests.
-RegExpFilter.typeMap.OBJECT_SUBREQUEST = RegExpFilter.typeMap.OBJECT;
+// Chrome can't distinguish between OBJECT_SUBREQUEST and OBJECT requests.
+if (!("OBJECT_SUBREQUEST" in chrome.webRequest.ResourceType))
+  RegExpFilter.typeMap.OBJECT_SUBREQUEST = RegExpFilter.typeMap.OBJECT;
 
 // Map of content types reported by the browser to the respecitve content types
 // used by Adblock Plus. Other content types are simply mapped to OTHER.
 let resourceTypes = new Map(function*()
 {
   for (let type in RegExpFilter.typeMap)
     yield [type.toLowerCase(), type];
 
   yield ["sub_frame", "SUBDOCUMENT"];
 
@@ skipping 144 matching lines @@
   if (msg.requestType.toUpperCase() in chrome.webRequest.ResourceType)
     return false;
 
   return ext.webRequest.onBeforeRequest._dispatch(
      new URL(msg.url),
      msg.requestType,
      sender.page,
      sender.frame
   ).includes(false);
 });