
PASS HTMLElement constructor must throw a TypeError when NewTarget is equal to itself 
PASS HTMLElement constructor must throw a TypeError when NewTarget is equal to itself via a Proxy object 
PASS HTMLElement constructor must throw TypeError when it has not been defined by customElements.define 
PASS Custom element constructor must throw TypeError when it does not extend HTMLElement 
PASS Custom element constructor must throw TypeError when it does not extend the proper element interface 
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 
PASS HTMLElement constructor must only get .prototype once, calling proxy constructor directly 
PASS HTMLElement constructor must only get .prototype once, calling proxy constructor via Reflect 
PASS HTMLElement constructor must only get .prototype once, calling proxy constructor via Reflect with no inheritance 
FAIL HTMLElement constructor must not get .prototype until it finishes its extends sanity checks, calling proxy constructor directly assert_throws: Should not be able to construct an HTMLElement named 'button' function "function () { new countingProxy() }" did not throw
FAIL HTMLElement constructor must not get .prototype until it finishes its extends sanity checks, calling via Reflect assert_throws: Should not be able to construct an HTMLElement named 'button' function "function () { Reflect.construct(HTMLElement, [], countingProxy) }" did not throw
PASS HTMLElement constructor must not get .prototype until it finishes its registration sanity checks, calling proxy constructor directly 
PASS HTMLElement constructor must not get .prototype until it finishes its registration  sanity checks, calling via Reflect