LibWeb: Add hack to disable StyleInvalidator while parsing document

Running a StyleInvalidator for every attribute set in a new document
was making it impossible to load larger sites. :^)

Libraries/LibWeb/CSS/StyleInvalidator.cpp

@@ -33,6 +33,8 @@ namespace Web::CSS {
 StyleInvalidator::StyleInvalidator(DOM::Document& document)
     : m_document(document)
 {
+    if (!m_document.should_invalidate_styles_on_attribute_changes())
+        return;
     auto& style_resolver = m_document.style_resolver();
     m_document.for_each_in_subtree_of_type<DOM::Element>([&](auto& element) {
         m_elements_and_matching_rules_before.set(&element, style_resolver.collect_matching_rules(element));
@@ -42,6 +44,8 @@ StyleInvalidator::StyleInvalidator(DOM::Document& document)
 
 StyleInvalidator::~StyleInvalidator()
 {
+    if (!m_document.should_invalidate_styles_on_attribute_changes())
+        return;
     auto& style_resolver = m_document.style_resolver();
     m_document.for_each_in_subtree_of_type<DOM::Element>([&](auto& element) {
         auto maybe_matching_rules_before = m_elements_and_matching_rules_before.get(&element);

Libraries/LibWeb/DOM/Document.h

@@ -61,6 +61,9 @@ public:
     static NonnullRefPtr<Document> create(const URL& url = "about:blank") { return adopt(*new Document(url)); }
     virtual ~Document() override;
 
+    bool should_invalidate_styles_on_attribute_changes() const { return m_should_invalidate_styles_on_attribute_changes; }
+    void set_should_invalidate_styles_on_attribute_changes(bool b) { m_should_invalidate_styles_on_attribute_changes = b; }
+
     void set_url(const URL& url) { m_url = url; }
     URL url() const { return m_url; }
 
@@ -283,6 +286,8 @@ private:
     bool m_ready_for_post_load_tasks { false };
 
     NonnullRefPtr<DOMImplementation> m_implementation;
+
+    bool m_should_invalidate_styles_on_attribute_changes { true };
 };
 
 }

Libraries/LibWeb/HTML/Parser/HTMLDocumentParser.cpp

@@ -122,11 +122,13 @@ HTMLDocumentParser::HTMLDocumentParser(DOM::Document& document, const StringView
     : m_tokenizer(input, encoding)
     , m_document(document)
 {
+    m_document->set_should_invalidate_styles_on_attribute_changes(false);
     m_document->set_encoding(TextCodec::get_standardized_encoding(encoding));
 }
 
 HTMLDocumentParser::~HTMLDocumentParser()
 {
+    m_document->set_should_invalidate_styles_on_attribute_changes(true);
 }
 
 void HTMLDocumentParser::run(const URL& url)