LibWeb/HTML: Update get_an_elements_target() to current spec

Author: https://github.com/AtkinsSJ
Commit: 9254994687
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3402
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/shannonbooth
Reviewed-by: https://github.com/tcl3 ✅

Libraries/LibWeb/HTML/HTMLElement.cpp

@@ -907,21 +907,26 @@ Optional<ARIA::Role> HTMLElement::default_role() const
 }
 
 // https://html.spec.whatwg.org/multipage/semantics.html#get-an-element's-target
-String HTMLElement::get_an_elements_target() const
+String HTMLElement::get_an_elements_target(Optional<String> target) const
 {
-    // To get an element's target, given an a, area, or form element element, run these steps:
+    // To get an element's target, given an a, area, or form element element, and an optional string-or-null target (default null), run these steps:
 
-    // 1. If element has a target attribute, then return that attribute's value.
-    auto maybe_target = attribute(AttributeNames::target);
-    if (maybe_target.has_value())
-        return maybe_target.release_value();
+    // 1. If target is null, then:
+    if (!target.has_value()) {
+        // 1. If element has a target attribute, then set target to that attribute's value.
+        if (auto maybe_target = attribute(AttributeNames::target); maybe_target.has_value()) {
+            target = maybe_target.release_value();
+        }
+        // FIXME: 2. Otherwise, if element's node document contains a base element with a target attribute,
+        //    set target to the value of the target attribute of the first such base element.
+    }
 
-    // FIXME: 2. If element's node document contains a base element with a
-    // target attribute, then return the value of the target attribute of the
-    // first such base element.
+    // 2. If target is not null, and contains an ASCII tab or newline and a U+003C (<), then set target to "_blank".
+    if (target.has_value() && target->bytes_as_string_view().contains("\t\n\r"sv) && target->contains('<'))
+        target = "_blank"_string;
 
-    // 3. Return the empty string.
-    return String {};
+    // 3. Return target.
+    return target.value_or({});
 }
 
 // https://html.spec.whatwg.org/multipage/links.html#get-an-element's-noopener