LibWeb: Cache intrinsic sizes across layout runs

This change moves intrinsic sizes cache from
LayoutState, which is local to current layout run,
to layout nodes, so it could be reused between
layout runs. This optimization is possible because
we can guarantee that these measurements will
remain unchanged unless the style of the element
or any of its descendants changes.

For now, invalidation is implemented simply by
resetting cache on whole ancestors chain once we
figured that element needs layout update.
The case when layout is invalidated by DOM's
structural changes is covered by layout tree
invalidation that drops intrinsic sizes cache
along with layout nodes.

I measured improvement on couple websites:
- Mail list on GMail 28ms -> 6ms
- GitHub large code page 47ms -> 36ms
- Discord chat history 15ms -> 8ms
(Time does not include `commit()`)

Libraries/LibWeb/DOM/Node.h

@@ -91,6 +91,26 @@ enum class StyleInvalidationReason {
 #undef __ENUMERATE_STYLE_INVALIDATION_REASON
 };
 
+#define ENUMERATE_SET_NEEDS_LAYOUT_REASONS(X)         \
+    X(CharacterDataReplaceData)                       \
+    X(FinalizeACrossDocumentNavigation)               \
+    X(HTMLImageElementReactToChangesInTheEnvironment) \
+    X(HTMLImageElementUpdateTheImageData)             \
+    X(HTMLVideoElementSetVideoTrack)                  \
+    X(KeyframeEffect)                                 \
+    X(LayoutTreeUpdate)                               \
+    X(NavigableSetViewportSize)                       \
+    X(SVGImageElementFetchTheDocument)                \
+    X(StyleChange)
+
+enum class SetNeedsLayoutReason {
+#define ENUMERATE_SET_NEEDS_LAYOUT_REASON(e) e,
+    ENUMERATE_SET_NEEDS_LAYOUT_REASONS(ENUMERATE_SET_NEEDS_LAYOUT_REASON)
+#undef ENUMERATE_SET_NEEDS_LAYOUT_REASON
+};
+
+[[nodiscard]] StringView to_string(SetNeedsLayoutReason);
+
 class Node : public EventTarget
     , public TreeNode<Node> {
     WEB_PLATFORM_OBJECT(Node, EventTarget);
@@ -291,6 +311,10 @@ public:
     void set_needs_style_update(bool);
     void set_needs_style_update_internal(bool) { m_needs_style_update = true; }
 
+    bool needs_layout_update() const { return m_needs_layout_update; }
+    void set_needs_layout_update(SetNeedsLayoutReason);
+    void reset_needs_layout_update() { m_needs_layout_update = false; }
+
     bool child_needs_style_update() const { return m_child_needs_style_update; }
     void set_child_needs_style_update(bool b) { m_child_needs_style_update = b; }
 
@@ -528,6 +552,8 @@ protected:
     bool m_child_needs_style_update { false };
     bool m_entire_subtree_needs_style_update { false };
 
+    bool m_needs_layout_update { false };
+
     UniqueNodeID m_unique_id;
 
     // https://dom.spec.whatwg.org/#registered-observer-list