Make JsEngine::Evaluate() return a wrapper for v8::Value to accessdifferent variable types easily

test/GlobalJsObject.cpp

 #include <AdblockPlus.h>
 #include <gtest/gtest.h>
 
 #include "../src/Thread.h"
 
 TEST(GlobalJsObjectTest, SetTimeout)
 {
   AdblockPlus::JsEngine jsEngine(0, 0, 0);
   jsEngine.Evaluate("setTimeout(function() {foo = 'bar';}, 100)");
-  ASSERT_EQ("undefined", jsEngine.Evaluate("typeof foo"));
+  ASSERT_TRUE(jsEngine.Evaluate("this.foo")->IsUndefined());
   AdblockPlus::Sleep(200);
-  ASSERT_EQ("bar", jsEngine.Evaluate("foo"));
+  ASSERT_EQ("bar", jsEngine.Evaluate("this.foo")->AsString());
 }
 
 TEST(GlobalJsObjectTest, SetTimeoutWithArgs)
 {
   AdblockPlus::JsEngine jsEngine(0, 0, 0);
   jsEngine.Evaluate("setTimeout(function(s) {foo = s;}, 100, 'foobar')");
-  ASSERT_EQ("undefined", jsEngine.Evaluate("typeof foo"));
+  ASSERT_TRUE(jsEngine.Evaluate("this.foo")->IsUndefined());
   AdblockPlus::Sleep(200);
-  ASSERT_EQ("foobar", jsEngine.Evaluate("foo"));
+  ASSERT_EQ("foobar", jsEngine.Evaluate("this.foo")->AsString());
 }
 
 TEST(GlobalJsObjectTest, SetTimeoutWithInvalidArgs)
 {
   AdblockPlus::JsEngine jsEngine(0, 0, 0);
   ASSERT_ANY_THROW(jsEngine.Evaluate("setTimeout()"));
   ASSERT_ANY_THROW(jsEngine.Evaluate("setTimeout('', 1)"));
   ASSERT_ANY_THROW(jsEngine.Evaluate("setTimeout(function(){}, '')"));
 }
 
 TEST(GlobalJsObjectTest, SetMultipleTimeouts)
 {
   AdblockPlus::JsEngine jsEngine(0, 0, 0);
   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("foo"));
+  ASSERT_EQ("1,2", jsEngine.Evaluate("this.foo")->AsString());
 }