LibWeb: Make factory method of DOM::DocumentType fallible

Userland/Libraries/LibWeb/DOM/DOMImplementation.cpp

@@ -114,7 +114,7 @@ JS::NonnullGCPtr<Document> DOMImplementation::create_html_document(DeprecatedStr
 WebIDL::ExceptionOr<JS::NonnullGCPtr<DocumentType>> DOMImplementation::create_document_type(DeprecatedString const& qualified_name, DeprecatedString const& public_id, DeprecatedString const& system_id)
 {
     TRY(Document::validate_qualified_name(realm(), qualified_name));
-    auto document_type = DocumentType::create(document());
+    auto document_type = TRY(DocumentType::create(document()));
     document_type->set_name(qualified_name);
     document_type->set_public_id(public_id);
     document_type->set_system_id(system_id);

Userland/Libraries/LibWeb/DOM/DocumentType.cpp

@@ -9,9 +9,9 @@
 
 namespace Web::DOM {
 
-JS::NonnullGCPtr<DocumentType> DocumentType::create(Document& document)
+WebIDL::ExceptionOr<JS::NonnullGCPtr<DocumentType>> DocumentType::create(Document& document)
 {
-    return document.heap().allocate<DocumentType>(document.realm(), document).release_allocated_value_but_fixme_should_propagate_errors();
+    return MUST_OR_THROW_OOM(document.heap().allocate<DocumentType>(document.realm(), document));
 }
 
 DocumentType::DocumentType(Document& document)

Userland/Libraries/LibWeb/DOM/DocumentType.h

@@ -18,7 +18,7 @@ class DocumentType final
     WEB_PLATFORM_OBJECT(DocumentType, Node);
 
 public:
-    static JS::NonnullGCPtr<DocumentType> create(Document&);
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<DocumentType>> create(Document&);
 
     virtual ~DocumentType() override = default;