Issue 4692 - Dont' keep a strong reference from timer thread

test/GlobalJsObject.cpp

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 37 matching lines @@
 }
 
 TEST_F(GlobalJsObjectTest, SetMultipleTimeouts)
 {
   jsEngine->Evaluate("foo = []");
   jsEngine->Evaluate("setTimeout(function(s) {foo.push('1');}, 100)");
   jsEngine->Evaluate("setTimeout(function(s) {foo.push('2');}, 150)");
   AdblockPlus::Sleep(200);
   ASSERT_EQ("1,2", jsEngine->Evaluate("this.foo")->AsString());
 }
+
+TEST_F(GlobalJsObjectTest, TimeoutDoesNotKeepJsEngine)
+{
+  jsEngine->Evaluate("setTimeout(function() {}, 50000)");
+  EXPECT_EQ(1u, jsEngine.use_count()); // check that counter is still 1
+  AdblockPlus::Sleep(200);
+  std::weak_ptr<AdblockPlus::JsEngine> weakJsEngine = jsEngine;
+  jsEngine.reset();
+  EXPECT_FALSE(weakJsEngine.lock());
+}