spec for __define[GS]etter__ and __lookup[GS]etter__

Based on
https://gist.github.com/anba/9140946#jsc-sourcejavascriptcoreruntimeobje
ctprototypecpp

spec.html

@@ -36111,6 +36111,64 @@ <h1>set Object.prototype.__proto__</h1>
           </emu-alg>
         </emu-annex>
       </emu-annex>
+
+      <emu-annex id="sec-object.prototype.__defineGetter__">
+        <h1>Object.prototype.__defineGetter__ (_P_, _getter_)</h1>
+        <p>When the `__defineGetter__` method is called with arguments _P_ and _getter_, the following steps are taken:</p>
+        <emu-alg>
+          1. Let _O_ be ? ToObject(*this* value).
+          1. If IsCallable(_getter_) is *false*, throw a *TypeError* exception.
+          1. Let _desc_ be PropertyDescriptor{[[Get]]: getter, [[Enumerable]]: *true*, [[Configurable]]: *true*}.
+          1. Let _key_ be ? ToPropertyKey(_P_).
+          1. Perform ? DefinePropertyOrThrow(O, _key_, _desc_).
+          1. Return *undefined*.
+        </emu-alg>
+      </emu-annex>
+
+      <emu-annex id="sec-object.prototype.__defineSetter__">
+        <h1>Object.prototype.__defineSetter__ (_P_, _setter_)</h1>
+        <p>When the `__defineSetter__` method is called with arguments _P_ and _setter_, the following steps are taken:</p>
+        <emu-alg>
+          1. Let _O_ be ? ToObject(*this* value).
+          1. If IsCallable(_setter_) is *false*, throw a *TypeError* exception.
+          1. Let _desc_ be PropertyDescriptor{[[Set]]: _setter_, [[Enumerable]]: *true*, [[Configurable]]: *true*}.
+          1. Let _key_ be ? ToPropertyKey(_P_).
+          1. Perform ? DefinePropertyOrThrow(O, _key_, _desc_).
+          1. Return *undefined*.
+        </emu-alg>
+      </emu-annex>
+
+      <emu-annex id="sec-object.prototype.__lookupGetter__">
+        <h1>Object.prototype.__lookupGetter__ (_P_)</h1>
+        <p>When the `__lookupGetter__` method is called with argument _P_, the following steps are taken:</p>
+        <emu-alg>
+          1. Let _O_ be ? ToObject(*this* value).
+          1. Let _key_ be ? ToPropertyKey(_P_).
+          1. Repeat
+            1. Let _desc_ be ? O.[[GetOwnProperty]](_key_).
+            1. If _desc_ is not *undefined*, then
+              1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Get]].
+              1. Return *undefined*.
+            1. Let _O_ be ? _O_.[[GetPrototypeOf]]().
+            1. If _O_ is *null*, return *undefined*.
+        </emu-alg>
+      </emu-annex>
+
+      <emu-annex id="sec-object.prototype.__lookupSetter__">
+        <h1>Object.prototype.__lookupSetter__ (_P_)</h1>
+        <p>When the `__lookupSetter__` method is called with argument _P_, the following steps are taken:</p>
+        <emu-alg>
+          1. Let _O_ be ? ToObject(*this* value).
+          1. Let _key_ be ? ToPropertyKey(_P_).
+          1. Repeat
+            1. Let _desc_ be ? O.[[GetOwnProperty]](_key_).
+            1. If _desc_ is not *undefined*, then
+              1. If IsAccessorDescriptor(_desc_) is *true*, return _desc_.[[Set]].
+              1. Return *undefined*.
+            1. Let _O_ be ? _O_.[[GetPrototypeOf]]().
+            1. If _O_ is *null*, return *undefined*.
+        </emu-alg>
+      </emu-annex>
     </emu-annex>
 
     <!-- es6num="B.2.3" -->