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/Layout/Progress.cpp

@@ -15,9 +15,7 @@ Progress::Progress(DOM::Document& document, HTML::HTMLProgressElement& element,
     set_intrinsic_height(12);
 }
 
-Progress::~Progress()
-{
-}
+Progress::~Progress() = default;
 
 RefPtr<Painting::Paintable> Progress::create_paintable() const
 {