LibWeb: Remove most uses of the old HTML parser

The only remaining client of the old parser is the fragment parser used
by the Element.innerHTML setter. We'll need to implement a bit more
stuff in the new parser before we can switch that over.

Libraries/LibWeb/Parser/HTMLDocumentParser.cpp

@@ -46,6 +46,13 @@
 
 namespace Web {
 
+RefPtr<Document> parse_html_document(const StringView& data, const URL& url, const String& encoding)
+{
+    HTMLDocumentParser parser(data, encoding);
+    parser.run(url);
+    return parser.document();
+}
+
 HTMLDocumentParser::HTMLDocumentParser(const StringView& input, const String& encoding)
     : m_tokenizer(input, encoding)
 {