Libraries: Use default constructors/destructors in LibWeb

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/LibWeb/HTML/Scripting/ClassicScript.cpp

@@ -152,8 +152,6 @@ ClassicScript::ClassicScript(AK::URL base_url, String filename, EnvironmentSetti
 {
 }
 
-ClassicScript::~ClassicScript()
-{
-}
+ClassicScript::~ClassicScript() = default;
 
 }