LibWeb: Make a handful of layout node leaf classes `final`

Userland/Libraries/LibWeb/Layout/ButtonBox.h

@@ -11,7 +11,7 @@
 
 namespace Web::Layout {
 
-class ButtonBox : public FormAssociatedLabelableNode {
+class ButtonBox final : public FormAssociatedLabelableNode {
     JS_CELL(ButtonBox, FormAssociatedLabelableNode);
 
 public:

Userland/Libraries/LibWeb/Layout/CanvasBox.h

@@ -11,7 +11,7 @@
 
 namespace Web::Layout {
 
-class CanvasBox : public ReplacedBox {
+class CanvasBox final : public ReplacedBox {
     JS_CELL(CanvasBox, ReplacedBox);
 
 public:

Userland/Libraries/LibWeb/Layout/CheckBox.h

@@ -11,7 +11,7 @@
 
 namespace Web::Layout {
 
-class CheckBox : public FormAssociatedLabelableNode {
+class CheckBox final : public FormAssociatedLabelableNode {
     JS_CELL(CheckBox, FormAssociatedLabelableNode);
 
 public:

Userland/Libraries/LibWeb/Layout/InlineNode.h

@@ -10,7 +10,7 @@
 
 namespace Web::Layout {
 
-class InlineNode : public NodeWithStyleAndBoxModelMetrics {
+class InlineNode final : public NodeWithStyleAndBoxModelMetrics {
     JS_CELL(InlineNode, NodeWithStyleAndBoxModelMetrics);
 
 public:

Userland/Libraries/LibWeb/Layout/Progress.h

@@ -11,7 +11,7 @@
 
 namespace Web::Layout {
 
-class Progress : public LabelableNode {
+class Progress final : public LabelableNode {
     JS_CELL(Progress, LabelableNode);
 
 public:

Userland/Libraries/LibWeb/Layout/TextNode.h

@@ -14,7 +14,7 @@ namespace Web::Layout {
 
 class LineBoxFragment;
 
-class TextNode : public Node {
+class TextNode final : public Node {
     JS_CELL(TextNode, Node);
 
 public: