Libraries: Use default constructors/destructors in LibJS

https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#cother-other-default-operation-rules

"The compiler is more likely to get the default semantics right and
you cannot implement these functions better than the compiler."

Userland/Libraries/LibJS/Script.cpp

@@ -35,9 +35,4 @@ Script::Script(Realm& realm, StringView filename, NonnullRefPtr<Program> parse_n
     , m_host_defined(host_defined)
 {
 }
-
-Script::~Script()
-{
-}
-
 }