LibWeb: Fire change events on deletion in FormAssociated Text Elements

Previously we would only trigger change events on insertion, which
resulted in javascript code missing changes due to deletion.

This makes the calculator on the MDN simple web worker demo update on
deletion as well.

Libraries/LibWeb/DOM/Node.h

@@ -62,6 +62,7 @@ enum class ShouldComputeRole {
     X(DidLoseFocus)                                 \
     X(DidReceiveFocus)                              \
     X(EditingInsertion)                             \
+    X(EditingDeletion)                              \
     X(ElementAttributeChange)                       \
     X(ElementSetShadowRoot)                         \
     X(HTMLDialogElementSetIsModal)                  \

Libraries/LibWeb/HTML/FormAssociatedElement.cpp

@@ -880,6 +880,9 @@ void FormAssociatedTextControlElement::handle_delete(DeleteDirection direction)
     }
 
     MUST(set_range_text({}, selection_start, selection_end, Bindings::SelectionMode::End));
+
+    text_node->invalidate_style(DOM::StyleInvalidationReason::EditingDeletion);
+    did_edit_text_node();
 }
 
 EventResult FormAssociatedTextControlElement::handle_return_key(FlyString const&)