Simplify the definition of the "entry" concept

It turns out that the "entrance counter" concept was unnecessary.
Whenever we run script, we increment it, and whenever we clean up after
running script, we decrement it. So it is always nonzero. Thus we can
simply look for whether it's a realm execution context.

Fixes #2441.

source

@@ -87622,9 +87622,6 @@ interface <dfn>NavigatorOnLine</dfn> {
 
   <ol>
 
-   <li><p>Increment <var>settings</var>'s <span>realm execution context</span>'s <span>entrance
-   counter</span> by one.</p></li>
-
    <li><p>Push <var>settings</var>'s <span>realm execution context</span> onto the <span>JavaScript
    execution context stack</span>; it is now the <span>running JavaScript execution
    context</span>.</p></li>
@@ -87642,9 +87639,6 @@ interface <dfn>NavigatorOnLine</dfn> {
    <li><p>Remove <var>settings</var>'s <span>realm execution context</span> from the
    <span>JavaScript execution context stack</span>.</p></li>
 
-   <li><p>Decrement <var>settings</var>'s <span>realm execution context</span>'s <span>entrance
-   counter</span> by one.</p></li>
-
    <li><p>If the <span>JavaScript execution context stack</span> is now empty, <span>perform a
    microtask checkpoint</span>. (If this runs scripts, these algorithms will be invoked
    reentrantly.)</p></li>
@@ -87871,15 +87865,15 @@ interface <dfn>NavigatorOnLine</dfn> {
 
   <h6>Entry</h6>
 
-  <p>All <span data-x="realm execution context">realm execution contexts</span> must contain, as
-  part of their code evaluation state, an <dfn>entrance counter</dfn> value, which is initially
-  zero. In the process of <a href="#calling-scripts">calling scripts</a>, this value will be
-  incremented and decremented.</p>
+  <p>The process of <a href="#calling-scripts">calling scripts</a> will push or pop <span
+  data-x="realm execution context">realm execution contexts</span> onto the <span>JavaScript
+  execution context stack</span>, interspersed with other <span data-x="JavaScript execution
+  context">execution contexts</span>.</p>
 
   <p>With this in hand, we define the <dfn>entry execution context</dfn> to be the most recently
-  pushed entry in the <span>JavaScript execution context stack</span> whose <span>entrance
-  counter</span> value is greater than zero. The <dfn data-x="concept-entry-realm">entry Realm</dfn>
-  is the <span>entry execution context</span>'s Realm component.</p>
+  pushed item in the <span>JavaScript execution context stack</span> that is a <span data-x="realm
+  execution context">realm execution context</span>. The <dfn data-x="concept-entry-realm">entry
+  Realm</dfn> is the <span>entry execution context</span>'s Realm component.</p>
 
   <p>Then, the <dfn>entry settings object</dfn> is the <span
   data-x="concept-realm-settings-object">environment settings object</span> of the <span
@@ -120236,8 +120230,8 @@ INSERT INTERFACES HERE
   Jellybean Stonerfish,
   Jens Bannmann,
   Jens Fendler,
-  Jens Lindstr&ouml;m,
   Jens Oliver Meiert,
+  Jens Widell,
   Jer Noble,
   Jeremey Hustman,
   Jeremy Keith,