LibJS+LibWeb: Pass prototype to Object constructor

Everyone who constructs an Object must now pass a prototype object when
applicable. There's still a fair amount of code that passes something
fetched from the Interpreter, but this brings us closer to being able
to detach prototypes from Interpreter eventually.

Libraries/LibJS/Runtime/NativeProperty.cpp

@@ -30,7 +30,8 @@
 namespace JS {
 
 NativeProperty::NativeProperty(AK::Function<Value(Interpreter&)> getter, AK::Function<void(Interpreter&, Value)> setter)
-    : m_getter(move(getter))
+    : Object(nullptr)
+    , m_getter(move(getter))
     , m_setter(move(setter))
 {
 }