Define "relevant settings object" for any platform object

PR: #564

source

@@ -2852,7 +2852,9 @@ a.setAttribute('href', 'http://example.com/'); // change the content attribute d
      <li><dfn data-noexport="">Supported property names</dfn>
      <li><dfn data-noexport="">Unenumerable</dfn>
      <li><dfn data-noexport="">Determine the value of a named property</dfn>
+     <li><dfn data-noexport="" data-x-href="https://heycam.github.io/webidl/#dfn-platform-object">Platform object</dfn></li>
      <li><dfn data-noexport="">Platform array objects</dfn>
+     <li><dfn data-noexport="" data-x-href="https://heycam.github.io/webidl/#es-platform-objects">Global environment associated with</dfn> a platform object</li>
      <li><dfn data-noexport="" data-x="dfn-read-only-array">Read only</dfn> (when applied to arrays)
      <li><dfn data-noexport="" data-x="dfn-callback-this-value">Callback this value</dfn>
      <li><dfn data-noexport="" data-x="concept-idl-convert" data-x-href="https://heycam.github.io/webidl/#es-type-mapping">Converting</dfn> between WebIDL types and JS types
@@ -85821,9 +85823,13 @@ interface <dfn>NavigatorOnLine</dfn> {
   <p>An <span>environment settings object</span>'s <dfn data-x="environment settings object's
   Realm">Realm</dfn> is its <span>realm execution context</span>'s Realm component.</p>
 
-  <p>The <dfn>relevant settings object for a global object</dfn> <var>o</var> is the
-  <span>environment settings object</span> whose <span>global object</span> is <var>o</var>.
-  (There is always a 1:1 mapping of global objects to environment settings objects.)</p>
+  <p id="relevant-settings-object-for-a-global-object">The <dfn>relevant settings object</dfn> for a
+  <span>global object</span> <var>o</var> is the <span>environment settings object</span> whose
+  <span>global object</span> is <var>o</var>. The <span>relevant settings object</span> for a
+  non-global <span>platform object</span> <var>o</var> is the <span>environment settings
+  object</span> whose <span>global object</span> is the global object of the <span>global
+  environment associated with</span> <var>o</var>. (There is always a 1:1 mapping of global objects
+  to environment settings objects.)</p>
 
   <p>The <dfn>script corresponding to the running execution context</dfn> is the
   <span>script</span> in the [[HostDefined]] slot of the <span>running JavaScript execution
@@ -118340,6 +118346,7 @@ INSERT INTERFACES HERE
   Jeff Cutsinger,
   Jeff Schiller,
   Jeff Walden,
+  Jeffrey Yasskin,
   Jeffrey Zeldman,
   &#32993;&#24935;&#37586; (Jennifer Braithwaite),
   Jens Bannmann,