AK: Correctly set host when parsing URL with a base file:// host

We were completely missing this spec step here. Also leave a FIXME for
the pre-existing implementation of this step, as this doesn't match the
spec.

AK/URLParser.cpp

@@ -1377,6 +1377,9 @@ URL URLParser::basic_parse(StringView raw_input, Optional<URL> const& base_url,
                 // 1. If base is non-null and base’s scheme is "file", then:
                 if (base_url.has_value() && base_url->m_scheme == "file") {
                     // 1. Set url’s host to base’s host.
+                    url->m_host = base_url->m_host;
+
+                    // FIXME: The spec does not seem to mention these steps.
                     url->m_paths = base_url->m_paths;
                     url->m_paths.remove(url->m_paths.size() - 1);
 

Tests/LibWeb/Text/expected/URL/url.txt

@@ -58,3 +58,13 @@ port => ''
 pathname => '/cat'
 search => '?dog'
 hash => '#meow%22woof'
+new URL('/hello', 'file://friends/')
+protocol => 'file:'
+username => ''
+password => ''
+host => 'friends'
+hostname => 'friends'
+port => ''
+pathname => '/hello'
+search => ''
+hash => ''

Tests/LibWeb/Text/input/URL/url.html

@@ -26,6 +26,7 @@
             { input: 'http://[1:1:0:0:1:0:0:0]/' },
             { input: 'unknown://serenityos.org:0' },
             { input: 'http://serenityos.org/cat?dog#meow"woof' },
+            { input: '/hello', base: 'file://friends/' },
         ]) {
             printURL(url.input, url.base);
         }