Make window.window/frames/self deal with no browsing context

Tests: ...

Helps with #4363.

source

@@ -3022,7 +3022,8 @@ a.setAttribute('href', 'https://example.com/'); // change the content attribute
          <dfn>@@toPrimitive</dfn>, and
          <dfn>@@toStringTag</dfn></li>
      <li><dfn data-x-href="https://tc39.github.io/ecma262/#sec-well-known-intrinsic-objects">Well-Known Intrinsic Objects</dfn>, including
-         <dfn data-x-href="https://tc39.github.io/ecma262/#sec-properties-of-the-array-prototype-object">%ArrayPrototype%</dfn> and
+         <dfn data-x-href="https://tc39.github.io/ecma262/#sec-properties-of-the-array-prototype-object">%ArrayPrototype%</dfn>,
+         <dfn data-x-href="https://tc39.github.io/ecma262/#sec-global-this">%GlobalThisValue%</dfn>, and
          <dfn data-x-href="https://tc39.github.io/ecma262/#sec-object.prototype.valueof">%ObjProto_valueOf%</dfn></li>
 
      <li>The <dfn data-x="js-prod-FunctionBody" data-x-href="https://tc39.github.io/ecma262/#prod-FunctionBody"><i>FunctionBody</i></dfn> production</li>
@@ -78539,9 +78540,10 @@ dictionary <dfn>WindowPostMessageOptions</dfn> : <span>PostMessageOptions</span>
   <span>browsing context</span>.</span></p>
 
   <p>The <dfn><code data-x="dom-window">window</code></dfn>, <dfn><code
-  data-x="dom-frames">frames</code></dfn>, and <dfn><code data-x="dom-self">self</code></dfn> IDL
-  attributes, on getting, must all return this <code>Window</code> object's <span>browsing
-  context</span>'s <code>WindowProxy</code> object.</p>
+  data-x="dom-frames">frames</code></dfn>, and <dfn><code data-x="dom-self">self</code></dfn>
+  attributes' getters must return this <code>Window</code> object's <span
+  data-x="concept-relevant-realm">relevant
+  Realm</span>.[[Intrinsics]].[[<span>%GlobalThisValue%</span>]].</p>
 
   <p>The <dfn><code data-x="dom-document">document</code></dfn> IDL attribute, on getting, must
   return this <code>Window</code> object's <span data-x="concept-document-window">associated