LibWeb: Move style element hooks to StyleElementBase

Move HTMLStyleElement's dynamic update handling, media/type attribute
handling, and script-blocking predicate skeleton into StyleElementBase
so style elements can share that plumbing.

Libraries/LibWeb/DOM/StyleElementBase.cpp

@@ -14,11 +14,27 @@
 #include <LibWeb/DOM/Event.h>
 #include <LibWeb/DOM/ShadowRoot.h>
 #include <LibWeb/DOM/StyleElementBase.h>
+#include <LibWeb/HTML/AttributeNames.h>
 #include <LibWeb/HTML/EventNames.h>
 #include <LibWeb/Infra/Strings.h>
 
 namespace Web::DOM {
 
+void StyleElementBase::update_a_style_block_for_dynamic_change()
+{
+    update_a_style_block();
+}
+
+void StyleElementBase::style_element_attribute_changed(FlyString const& name, Optional<String> const& value)
+{
+    if (name == HTML::AttributeNames::media) {
+        if (auto* sheet = this->sheet())
+            sheet->set_media(value.value_or({}));
+    } else if (name == HTML::AttributeNames::type) {
+        update_a_style_block_for_dynamic_change();
+    }
+}
+
 // The user agent must run the "update a style block" algorithm whenever one of the following conditions occur:
 // FIXME: The element is popped off the stack of open elements of an HTML parser or XML parser.
 //
@@ -152,6 +168,29 @@ void StyleElementBase::finished_loading_critical_subresources(AnyFailed any_fail
     m_document_load_event_delayer.clear();
 }
 
+// https://html.spec.whatwg.org/multipage/semantics.html#contributes-a-script-blocking-style-sheet
+bool StyleElementBase::style_element_contributes_a_script_blocking_style_sheet() const
+{
+    // An element el in the context of a Document of an HTML parser or XML parser
+    // contributes a script-blocking style sheet if all of the following are true:
+
+    // FIXME: el was created by that Document's parser.
+
+    // el is either a style element or a link element that was an external resource link that contributes to the styling processing model when the el was created by the parser.
+    // NOTE: This is a style element, so all good!
+
+    // FIXME: el's media attribute's value matches the environment.
+
+    // FIXME: el's style sheet was enabled when the element was created by the parser.
+
+    // FIXME: The last time the event loop reached step 1, el's root was that Document.
+
+    // FIXME: The user agent hasn't given up on loading that particular style sheet yet.
+    //        A user agent may give up on loading a style sheet at any time.
+
+    return false;
+}
+
 // https://www.w3.org/TR/cssom/#dom-linkstyle-sheet
 CSS::CSSStyleSheet* StyleElementBase::sheet()
 {

Libraries/LibWeb/DOM/StyleElementBase.h

@@ -18,6 +18,8 @@ public:
     virtual ~StyleElementBase() = default;
 
     void update_a_style_block();
+    void update_a_style_block_for_dynamic_change();
+    void style_element_attribute_changed(FlyString const&, Optional<String> const& value);
 
     CSS::CSSStyleSheet* sheet();
     CSS::CSSStyleSheet const* sheet() const;
@@ -34,6 +36,10 @@ public:
     void visit_style_element_edges(JS::Cell::Visitor&);
 
     virtual Element& as_element() = 0;
+    virtual Element const& as_element() const = 0;
+
+protected:
+    bool style_element_contributes_a_script_blocking_style_sheet() const;
 
 private:
     // https://www.w3.org/TR/cssom/#associated-css-style-sheet

Libraries/LibWeb/HTML/HTMLStyleElement.cpp

@@ -7,8 +7,6 @@
  */
 
 #include <LibWeb/Bindings/HTMLStyleElement.h>
-#include <LibWeb/CSS/StyleComputer.h>
-#include <LibWeb/DOM/Document.h>
 #include <LibWeb/HTML/HTMLStyleElement.h>
 
 namespace Web::HTML {
@@ -37,31 +35,25 @@ void HTMLStyleElement::visit_edges(Cell::Visitor& visitor)
 void HTMLStyleElement::children_changed(ChildrenChangedMetadata const& metadata)
 {
     Base::children_changed(metadata);
-    update_a_style_block();
+    update_a_style_block_for_dynamic_change();
 }
 
 void HTMLStyleElement::inserted()
 {
     Base::inserted();
-    update_a_style_block();
+    update_a_style_block_for_dynamic_change();
 }
 
 void HTMLStyleElement::removed_from(IsSubtreeRoot is_subtree_root, Node* old_ancestor, Node& old_root)
 {
     Base::removed_from(is_subtree_root, old_ancestor, old_root);
-    update_a_style_block();
+    update_a_style_block_for_dynamic_change();
 }
 
 void HTMLStyleElement::attribute_changed(FlyString const& name, Optional<String> const& old_value, Optional<String> const& value, Optional<FlyString> const& namespace_)
 {
     Base::attribute_changed(name, old_value, value, namespace_);
-
-    if (name == HTML::AttributeNames::media) {
-        if (auto* sheet = this->sheet())
-            sheet->set_media(value.value_or({}));
-    } else if (name == HTML::AttributeNames::type) {
-        update_a_style_block();
-    }
+    style_element_attribute_changed(name, value);
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#dom-style-disabled
@@ -94,24 +86,7 @@ void HTMLStyleElement::set_disabled(bool disabled)
 // https://html.spec.whatwg.org/multipage/semantics.html#contributes-a-script-blocking-style-sheet
 bool HTMLStyleElement::contributes_a_script_blocking_style_sheet() const
 {
-    // An element el in the context of a Document of an HTML parser or XML parser
-    // contributes a script-blocking style sheet if all of the following are true:
-
-    // FIXME: el was created by that Document's parser.
-
-    // el is either a style element or a link element that was an external resource link that contributes to the styling processing model when the el was created by the parser.
-    // NOTE: This is a style element, so all good!
-
-    // FIXME: el's media attribute's value matches the environment.
-
-    // FIXME: el's style sheet was enabled when the element was created by the parser.
-
-    // FIXME: The last time the event loop reached step 1, el's root was that Document.
-
-    // FIXME: The user agent hasn't given up on loading that particular style sheet yet.
-    //        A user agent may give up on loading a style sheet at any time.
-
-    return false;
+    return style_element_contributes_a_script_blocking_style_sheet();
 }
 
 }

Libraries/LibWeb/HTML/HTMLStyleElement.h

@@ -39,6 +39,7 @@ private:
 
     // ^DOM::StyleElementBase
     virtual Element& as_element() override { return *this; }
+    virtual Element const& as_element() const override { return *this; }
 
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;

Libraries/LibWeb/SVG/SVGStyleElement.h

@@ -32,6 +32,7 @@ private:
 
     // ^DOM::StyleElementBase
     virtual Element& as_element() override { return *this; }
+    virtual Element const& as_element() const override { return *this; }
 
     virtual void initialize(JS::Realm&) override;
     virtual void visit_edges(Cell::Visitor&) override;