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/EventLoop/TaskQueue.cpp

@@ -14,9 +14,7 @@ TaskQueue::TaskQueue(HTML::EventLoop& event_loop)
 {
 }
 
-TaskQueue::~TaskQueue()
-{
-}
+TaskQueue::~TaskQueue() = default;
 
 void TaskQueue::add(NonnullOwnPtr<Task> task)
 {