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/HTMLProgressElement.cpp

@@ -15,9 +15,7 @@ HTMLProgressElement::HTMLProgressElement(DOM::Document& document, DOM::Qualified
 {
 }
 
-HTMLProgressElement::~HTMLProgressElement()
-{
-}
+HTMLProgressElement::~HTMLProgressElement() = default;
 
 RefPtr<Layout::Node> HTMLProgressElement::create_layout_node(NonnullRefPtr<CSS::StyleProperties> style)
 {