LibWeb: Fire a change event on input elements in the focus update steps

This ensures the change event is received before the blur event.

Userland/Libraries/LibWeb/HTML/HTMLInputElement.h

@@ -158,6 +158,9 @@ public:
     virtual bool has_activation_behavior() const override;
     virtual void activation_behavior(DOM::Event const&) override;
 
+    bool has_input_activation_behavior() const;
+    bool change_event_applies() const;
+
 private:
     HTMLInputElement(DOM::Document&, DOM::QualifiedName);