registerElement method Null safety
Deprecated: This is a legacy API based on a deprecated Web Components v0.5 specification. Web Components v0.5 doesn't work on modern browsers and can only be used with a polyfill.
The latest Web Components specification is supported indirectly via
JSInterop and doesn't have an explicit API in the dart:html
library.
Implementation
@deprecated
void registerElement(String tag, Type customElementClass,
{String? extendsTag}) {
registerElement2(
tag, {'prototype': customElementClass, 'extends': extendsTag});
}