This is a testharness.js-based test.
FAIL HTMLElement constructor must throw a TypeError when NewTarget is equal to itself assert_throws: function "function () { new HTMLElement(); }" did not throw
FAIL HTMLElement constructor must throw a TypeError when NewTarget is equal to itself via a Proxy object assert_throws: function "function () { new HTMLElement(); }" did not throw
PASS HTMLElement constructor must throw TypeError when it has not been defined by customElements.define 
PASS HTMLElement constructor must infer the tag name from the element interface 
PASS HTMLElement constructor must allow subclassing a custom element 
PASS HTMLElement constructor must allow subclassing an user-defined subclass of HTMLElement 
Harness: the test ran to completion.

