Don`t use references to JsEngine to avoid use-after-free errors,switch to shared_ptr instead

test/GlobalJsObject.cpp

 #include <AdblockPlus.h>
 #include <gtest/gtest.h>
 
 #include "../src/Thread.h"
 
 TEST(GlobalJsObjectTest, SetTimeout)
 {
-  AdblockPlus::JsEngine jsEngine;
-  jsEngine.Evaluate("setTimeout(function() {foo = 'bar';}, 100)");
-  ASSERT_TRUE(jsEngine.Evaluate("this.foo")->IsUndefined());
+  AdblockPlus::JsEnginePtr jsEngine(AdblockPlus::JsEngine::New());
+  jsEngine->Evaluate("setTimeout(function() {foo = 'bar';}, 100)");
+  ASSERT_TRUE(jsEngine->Evaluate("this.foo")->IsUndefined());
   AdblockPlus::Sleep(200);
-  ASSERT_EQ("bar", jsEngine.Evaluate("this.foo")->AsString());
+  ASSERT_EQ("bar", jsEngine->Evaluate("this.foo")->AsString());
 }
 
 TEST(GlobalJsObjectTest, SetTimeoutWithArgs)
 {
-  AdblockPlus::JsEngine jsEngine;
-  jsEngine.Evaluate("setTimeout(function(s) {foo = s;}, 100, 'foobar')");
-  ASSERT_TRUE(jsEngine.Evaluate("this.foo")->IsUndefined());
+  AdblockPlus::JsEnginePtr jsEngine(AdblockPlus::JsEngine::New());
+  jsEngine->Evaluate("setTimeout(function(s) {foo = s;}, 100, 'foobar')");
+  ASSERT_TRUE(jsEngine->Evaluate("this.foo")->IsUndefined());
   AdblockPlus::Sleep(200);
-  ASSERT_EQ("foobar", jsEngine.Evaluate("this.foo")->AsString());
+  ASSERT_EQ("foobar", jsEngine->Evaluate("this.foo")->AsString());
 }
 
 TEST(GlobalJsObjectTest, SetTimeoutWithInvalidArgs)
 {
-  AdblockPlus::JsEngine jsEngine;
-  ASSERT_ANY_THROW(jsEngine.Evaluate("setTimeout()"));
-  ASSERT_ANY_THROW(jsEngine.Evaluate("setTimeout('', 1)"));
+  AdblockPlus::JsEnginePtr jsEngine(AdblockPlus::JsEngine::New());
+  ASSERT_ANY_THROW(jsEngine->Evaluate("setTimeout()"));
+  ASSERT_ANY_THROW(jsEngine->Evaluate("setTimeout('', 1)"));
 }
 
 TEST(GlobalJsObjectTest, SetMultipleTimeouts)
 {
-  AdblockPlus::JsEngine jsEngine;
-  jsEngine.Evaluate("foo = []");
-  jsEngine.Evaluate("setTimeout(function(s) {foo.push('1');}, 100)");
-  jsEngine.Evaluate("setTimeout(function(s) {foo.push('2');}, 150)");
+  AdblockPlus::JsEnginePtr jsEngine(AdblockPlus::JsEngine::New());
+  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());
+  ASSERT_EQ("1,2", jsEngine->Evaluate("this.foo")->AsString());
 }