LibWeb: Make StyleBlockRule more accessible to outsiders

For our naive var() implementation, we need to be able to create
StyleBlockRules outside of the Parser, and these changes make that
possible.

Userland/Libraries/LibWeb/CSS/Parser/StyleBlockRule.h

@@ -19,12 +19,19 @@ class StyleBlockRule : public RefCounted<StyleBlockRule> {
 
 public:
     StyleBlockRule();
+    explicit StyleBlockRule(Token token, Vector<StyleComponentValueRule>&& values)
+        : m_token(token)
+        , m_values(move(values))
+    {
+    }
     ~StyleBlockRule();
 
     bool is_curly() const { return m_token.is(Token::Type::OpenCurly); }
     bool is_paren() const { return m_token.is(Token::Type::OpenParen); }
     bool is_square() const { return m_token.is(Token::Type::OpenSquare); }
 
+    Token const& token() const { return m_token; }
+
     Vector<StyleComponentValueRule> const& values() const { return m_values; }
 
     String to_string() const;