Normative: Remove steps 2 and 4 from ProxyCreate (#1814)

Fixes #1798.

spec.html

@@ -10326,9 +10326,7 @@ <h1>ProxyCreate ( _target_, _handler_ )</h1>
       <p>The abstract operation ProxyCreate takes arguments _target_ and _handler_. It is used to specify the creation of new Proxy exotic objects. It performs the following steps when called:</p>
       <emu-alg>
         1. If Type(_target_) is not Object, throw a *TypeError* exception.
-        1. If _target_ is a Proxy exotic object and _target_.[[ProxyHandler]] is *null*, throw a *TypeError* exception.
         1. If Type(_handler_) is not Object, throw a *TypeError* exception.
-        1. If _handler_ is a Proxy exotic object and _handler_.[[ProxyHandler]] is *null*, throw a *TypeError* exception.
         1. Let _P_ be ! MakeBasicObject(&laquo; [[ProxyHandler]], [[ProxyTarget]] &raquo;).
         1. Set _P_'s essential internal methods, except for [[Call]] and [[Construct]], to the definitions specified in <emu-xref href="#sec-proxy-object-internal-methods-and-internal-slots"></emu-xref>.
         1. If IsCallable(_target_) is *true*, then