API cleanup, get rid of JsObject and GetProperty() methods that don`t return JsValue

src/FilterEngine.cpp

 #include <algorithm>
 #include <cctype>
 #include <functional>
 
 #include <AdblockPlus.h>
 
 using namespace AdblockPlus;
 
 extern const char* jsSources[];
 
 Filter::Filter(JsValuePtr value)
-    : JsValue(value->jsEngine, value->value)
+    : JsValue(value)
 {
   if (!IsObject())
     throw std::runtime_error("JavaScript value is not an object");
 }
 
 Filter::Type Filter::GetType()
 {
   std::string className = GetClassName();
   if (className == "BlockingFilter")
     return TYPE_BLOCKING;
@@ skipping 32 matching lines @@
   params.push_back(shared_from_this());
   func->Call(params);
 }
 
 bool Filter::operator==(const Filter& filter) const
 {
   return GetProperty("text")->AsString() == filter.GetProperty("text")->AsString();
 }
 
 Subscription::Subscription(JsValuePtr value)
-    : JsValue(value->jsEngine, value->value)
+    : JsValue(value)
 {
   if (!IsObject())
     throw std::runtime_error("JavaScript value is not an object");
 }
 
 bool Subscription::IsListed()
 {
   JsValuePtr func = jsEngine->Evaluate("API.isListedFilter");
   JsValueList params;
   params.push_back(shared_from_this());
@@ skipping 110 matching lines @@
 {
   JsValuePtr func = jsEngine->Evaluate("API.getElementHidingSelectors");
   JsValueList params;
   params.push_back(jsEngine->NewValue(domain));
   JsValueList result = func->Call(params)->AsList();
   std::vector<std::string> selectors;
   for (JsValueList::iterator it = result.begin(); it != result.end(); ++it)
     selectors.push_back((*it)->AsString());
   return selectors;
 }