LibURL: Don't return early parsing a URL with an empty input

We can't simply use the base URL as it may need to be modified in some
form. For example - for the included test, the fragment was previously
being included in the resulting URL.

This fixes 1 test on https://wpt.live/url/url-constructor.any.html

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

@@ -128,6 +128,16 @@ port => ''
 pathname => '/c:/foo/bar'
 search => ''
 hash => ''
+new URL('', 'file:///test?test#test')
+protocol => 'file:'
+username => ''
+password => ''
+host => ''
+hostname => ''
+port => ''
+pathname => '/test'
+search => '?test'
+hash => ''
 =========================================
 URL.parse('ftp://serenityos.org:21', undefined)
 protocol => 'ftp:'
@@ -259,3 +269,13 @@ port => ''
 pathname => '/c:/foo/bar'
 search => ''
 hash => ''
+URL.parse('', 'file:///test?test#test')
+protocol => 'file:'
+username => ''
+password => ''
+host => ''
+hostname => ''
+port => ''
+pathname => '/test'
+search => '?test'
+hash => ''

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

@@ -34,6 +34,7 @@
             { input: 'h\tt\nt\rp://h\to\ns\rt:9\t0\n0\r0/p\ta\nt\rh?q\tu\ne\rry#f\tr\na\rg' },
             { input: '  \t', base: 'http://ladybird.org/foo/bar' },
             { input: '/c:/foo/bar', base: 'file:///c:/baz/qux' },
+            { input: '', base: 'file:///test?test#test' },
         ];
 
         for (url of urls) {

Userland/Libraries/LibURL/Parser.cpp

@@ -794,8 +794,6 @@ ErrorOr<String> Parser::percent_encode_after_encoding(StringView input, PercentE
 URL Parser::basic_parse(StringView raw_input, Optional<URL> const& base_url, Optional<URL> url, Optional<State> state_override)
 {
     dbgln_if(URL_PARSER_DEBUG, "URL::Parser::basic_parse: Parsing '{}'", raw_input);
-    if (raw_input.is_empty())
-        return base_url.has_value() ? *base_url : URL {};
 
     size_t start_index = 0;
     size_t end_index = raw_input.length();