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

test/ConsoleJsObject.cpp

 #include <AdblockPlus.h>
 #include <gtest/gtest.h>
 
 class MockErrorCallback : public AdblockPlus::ErrorCallback
 {
 public:
   std::string lastMessage;
 
   void operator()(const std::string& message)
   {
     lastMessage = message;
   }
 };
 
 TEST(ConsoleJsObjectTest, ErrorInvokesErrorCallback)
 {
   MockErrorCallback errorCallback;
   AdblockPlus::JsEngine jsEngine(0, 0, &errorCallback);
   jsEngine.Evaluate("console.error('foo')");
   ASSERT_EQ("foo", errorCallback.lastMessage);
 }
 
 TEST(ConsoleJsObjectTest, ErrorWithMultipleArguments)
 {
   MockErrorCallback errorCallback;
-  AdblockPlus::JsEngine jsEngine(0, &errorCallback);
+  AdblockPlus::JsEngine jsEngine(0, 0, &errorCallback);
   jsEngine.Evaluate("console.error('foo', 'bar')");
   ASSERT_EQ("foobar", errorCallback.lastMessage);
 }
 
 TEST(ConsoleJsObjectTest, TraceDoesNothing)
 {
   AdblockPlus::JsEngine jsEngine(0, 0, 0);
   jsEngine.Evaluate("console.trace()");
 }