LibWeb: Start exposing CSS style sheets to JavaScript :^)

This patch adds bindings for the following objects:

- StyleSheet
- StyleSheetList
- CSSStyleSheet

You can get to a document's style sheets via Document.styleSheets
and iterate through them using StyleSheetList's item() and length().

That's it in terms of functionality at this point, but still neat. :^)

Userland/Libraries/LibWeb/CSS/CSSStyleSheet.h

@@ -37,6 +37,8 @@ namespace Web::CSS {
 
 class CSSStyleSheet final : public StyleSheet {
 public:
+    using WrapperType = Bindings::CSSStyleSheetWrapper;
+
     static NonnullRefPtr<CSSStyleSheet> create(NonnullRefPtrVector<CSSRule> rules)
     {
         return adopt(*new CSSStyleSheet(move(rules)));
@@ -86,3 +88,9 @@ private:
 };
 
 }
+
+namespace Web::Bindings {
+
+CSSStyleSheetWrapper* wrap(JS::GlobalObject&, CSS::CSSStyleSheet&);
+
+}

Userland/Libraries/LibWeb/CSS/CSSStyleSheet.idl

@@ -0,0 +1,6 @@
+interface CSSStyleSheet : StyleSheet {
+    // readonly attribute CSSRule? ownerRule;
+    // [SameObject] readonly attribute CSSRuleList cssRules;
+    // unsigned long insertRule(CSSOMString rule, optional unsigned long index = 0);
+    // undefined deleteRule(unsigned long index);
+};

Userland/Libraries/LibWeb/CSS/StyleSheet.h

@@ -28,11 +28,17 @@
 #pragma once
 
 #include <AK/RefCounted.h>
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/Forward.h>
 
 namespace Web::CSS {
 
-class StyleSheet : public RefCounted<StyleSheet> {
+class StyleSheet
+    : public RefCounted<StyleSheet>
+    , public Bindings::Wrappable {
 public:
+    using WrapperType = Bindings::StyleSheetWrapper;
+
     virtual ~StyleSheet() = default;
 
 protected:

Userland/Libraries/LibWeb/CSS/StyleSheet.idl

@@ -0,0 +1,9 @@
+interface StyleSheet {
+    // readonly attribute CSSOMString type;
+    // readonly attribute USVString? href;
+    // readonly attribute (Element or ProcessingInstruction)? ownerNode;
+    // readonly attribute CSSStyleSheet? parentStyleSheet;
+    // readonly attribute DOMString? title;
+    // [SameObject, PutForwards=mediaText] readonly attribute MediaList media;
+    // attribute boolean disabled;
+};

Userland/Libraries/LibWeb/CSS/StyleSheetList.cpp

@@ -28,7 +28,7 @@
 
 namespace Web::CSS {
 
-void StyleSheetList::add_sheet(NonnullRefPtr<StyleSheet> sheet)
+void StyleSheetList::add_sheet(NonnullRefPtr<CSSStyleSheet> sheet)
 {
     m_sheets.append(move(sheet));
 }

Userland/Libraries/LibWeb/CSS/StyleSheetList.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * Copyright (c) 2020-2021, Andreas Kling <kling@serenityos.org>
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -28,27 +28,46 @@
 
 #include <AK/NonnullRefPtrVector.h>
 #include <AK/RefCounted.h>
-#include <LibWeb/CSS/StyleSheet.h>
+#include <LibWeb/Bindings/Wrappable.h>
+#include <LibWeb/CSS/CSSStyleSheet.h>
 #include <LibWeb/Forward.h>
 
 namespace Web::CSS {
 
-class StyleSheetList : public RefCounted<StyleSheetList> {
+class StyleSheetList
+    : public RefCounted<StyleSheetList>
+    , public Bindings::Wrappable {
 public:
+    using WrapperType = Bindings::StyleSheetListWrapper;
+
     static NonnullRefPtr<StyleSheetList> create(DOM::Document& document)
     {
         return adopt(*new StyleSheetList(document));
     }
 
-    void add_sheet(NonnullRefPtr<StyleSheet>);
+    void add_sheet(NonnullRefPtr<CSSStyleSheet>);
+    const NonnullRefPtrVector<CSSStyleSheet>& sheets() const { return m_sheets; }
 
-    const NonnullRefPtrVector<StyleSheet>& sheets() const { return m_sheets; }
+    RefPtr<CSSStyleSheet> item(size_t index) const
+    {
+        if (index >= m_sheets.size())
+            return {};
+        return m_sheets[index];
+    }
+
+    size_t length() const { return m_sheets.size(); }
 
 private:
     explicit StyleSheetList(DOM::Document&);
 
     DOM::Document& m_document;
-    NonnullRefPtrVector<StyleSheet> m_sheets;
+    NonnullRefPtrVector<CSSStyleSheet> m_sheets;
 };
 
 }
+
+namespace Web::Bindings {
+
+StyleSheetListWrapper* wrap(JS::GlobalObject&, CSS::StyleSheetList&);
+
+}

Userland/Libraries/LibWeb/CSS/StyleSheetList.idl

@@ -0,0 +1,5 @@
+interface StyleSheetList {
+    // FIXME: item() should be a WebIDL "getter"
+    CSSStyleSheet? item(unsigned long index);
+    readonly attribute unsigned long length;
+};