LibURL+Everywhere: Only percent decode URL paths when actually needed

Web specs do not return through javascript percent decoded URL path
components - but we were doing this in a number of places due to the
default behaviour of URL::serialize_path.

Since percent encoded URL paths may not contain valid UTF-8 - this was
resulting in us crashing in these places.

For example - on an HTMLAnchorElement when retrieving the pathname for
the URL of:

http://ladybird.org/foo%C2%91%91

To fix this make the URL class only return the percent encoded
serialized path, matching the URL spec. When the decoded path is
required instead explicitly call URL::percent_decode.

This fixes a crash running WPT URL tests for the anchor element on:

https://wpt.live/url/a-element.html

Userland/Libraries/LibWeb/HTML/HTMLHyperlinkElementUtils.cpp

@@ -291,10 +291,8 @@ String HTMLHyperlinkElementUtils::pathname() const
     if (!m_url.has_value())
         return String {};
 
-    // 4. If url's cannot-be-a-base-URL is true, then return url's path[0].
-    // 5. If url's path is empty, then return the empty string.
-    // 6. Return "/", followed by the strings in url's path (including empty strings), separated from each other by "/".
-    return MUST(String::from_byte_string(m_url->serialize_path()));
+    // 4. Return the result of URL path serializing url.
+    return m_url->serialize_path();
 }
 
 // https://html.spec.whatwg.org/multipage/links.html#dom-hyperlink-pathname

Userland/Libraries/LibWeb/HTML/Location.cpp

@@ -248,15 +248,13 @@ WebIDL::ExceptionOr<void> Location::set_port(String const&)
 // https://html.spec.whatwg.org/multipage/history.html#dom-location-pathname
 WebIDL::ExceptionOr<String> Location::pathname() const
 {
-    auto& vm = this->vm();
-
     // 1. If this's relevant Document is non-null and its origin is not same origin-domain with the entry settings object's origin, then throw a "SecurityError" DOMException.
     auto const relevant_document = this->relevant_document();
     if (relevant_document && !relevant_document->origin().is_same_origin_domain(entry_settings_object().origin()))
         return WebIDL::SecurityError::create(realm(), "Location's relevant document is not same origin-domain with the entry settings object's origin"_fly_string);
 
     // 2. Return the result of URL path serializing this Location object's url.
-    return TRY_OR_THROW_OOM(vm, String::from_byte_string(url().serialize_path()));
+    return url().serialize_path();
 }
 
 WebIDL::ExceptionOr<void> Location::set_pathname(String const&)

Userland/Libraries/LibWeb/HTML/WorkerLocation.cpp

@@ -92,11 +92,10 @@ WebIDL::ExceptionOr<String> WorkerLocation::port() const
 }
 
 // https://html.spec.whatwg.org/multipage/workers.html#dom-workerlocation-pathname
-WebIDL::ExceptionOr<String> WorkerLocation::pathname() const
+String WorkerLocation::pathname() const
 {
-    auto& vm = realm().vm();
     // The pathname getter steps are to return the result of URL path serializing this's WorkerGlobalScope object's url.
-    return TRY_OR_THROW_OOM(vm, String::from_byte_string(m_global_scope->url().serialize_path()));
+    return m_global_scope->url().serialize_path();
 }
 
 // https://html.spec.whatwg.org/multipage/workers.html#dom-workerlocation-search

Userland/Libraries/LibWeb/HTML/WorkerLocation.h

@@ -24,7 +24,7 @@ public:
     WebIDL::ExceptionOr<String> host() const;
     WebIDL::ExceptionOr<String> hostname() const;
     WebIDL::ExceptionOr<String> port() const;
-    WebIDL::ExceptionOr<String> pathname() const;
+    String pathname() const;
     WebIDL::ExceptionOr<String> search() const;
     WebIDL::ExceptionOr<String> hash() const;