Remove overly permissive "kill a worker" algorithm

There’s a new sheriff in town and workers can now no longer be killed.
“Kill” was a poor term to use anyway and also not needed as worker
termination already covered all angles we care about except for one.

Now, workers can solely be terminated due to close(), terminate(), or
disappearing documents.

Fixes #1004.

source

@@ -97436,8 +97436,7 @@ interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
 
     <p class="note">In addition to the usual possibilities of returning a value or failing due to
     an exception, this could be <span data-x="abort a running script">prematurely aborted</span> by
-    the "<span>kill a worker</span>" or "<span>terminate a worker</span>" algorithms defined
-    below.</p>
+    the <span>terminate a worker</span> algorithm defined below.</p>
    </li>
 
    <li><p>Enable <var>outside port</var>'s <span>port message queue</span>.</p></li>
@@ -97466,8 +97465,8 @@ interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
 
     <p class="note">The handling of events or the execution of callbacks by <span
     data-x="concept-task">tasks</span> run by the <span>event loop</span> might get <span
-    data-x="abort a running script">prematurely aborted</span> by the "<span>kill a worker</span>"
-    or "<span>terminate a worker</span>" algorithms defined below.</p>
+    data-x="abort a running script">prematurely aborted</span> by the <span>terminate a
+    worker</span> algorithm defined below.</p>
 
     <p class="note">The worker processing model remains on this step until the event loop is
     destroyed, which happens after the <span data-x="dom-WorkerGlobalScope-closing">closing</span>
@@ -97499,33 +97498,6 @@ interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
 
   <hr>
 
-  <p>When a user agent is to <dfn data-export="">kill a worker</dfn> it must run the following steps
-  <span>in parallel</span> with the worker's main loop (the "<span>run a worker</span>" processing
-  model defined above):</p>
-
-  <ol>
-
-   <li><p>Set the worker's <code>WorkerGlobalScope</code> object's <span
-   data-x="dom-WorkerGlobalScope-closing">closing</span> flag to true.</p></li>
-
-   <li><p>If there are any <span data-x="concept-task">tasks</span> queued in the
-   <code>WorkerGlobalScope</code> object's <span>event loop</span>'s <span data-x="task queue">task
-   queues</span>, discard them without processing them.</p></li>
-
-   <li><p>Wait a user-agent-defined amount of time.</p></li>
-
-   <li><p><span data-x="abort a running script">Abort the script</span> currently running in the
-   worker.</p></li>
-
-  </ol>
-
-  <p>User agents may invoke the "<span>kill a worker</span>" processing model on a worker at any
-  time, e.g. in response to user requests, in response to CPU quota management, or when a worker
-  stops being an <span>active needed worker</span> if the worker continues executing even after its
-  <span data-x="dom-WorkerGlobalScope-closing">closing</span> flag was set to true.</p>
-
-  <hr>
-
   <p>When a user agent is to <dfn data-export="">terminate a worker</dfn> it must run the following
   steps <span>in parallel</span> with the worker's main loop (the "<span>run a worker</span>"
   processing model defined above):</p>
@@ -97549,6 +97521,10 @@ interface <dfn>SharedWorkerGlobalScope</dfn> : <span>WorkerGlobalScope</span> {
 
   </ol>
 
+  <p>User agents may invoke the <span>terminate a worker</span> algorithm when a worker stops being
+  an <span>active needed worker</span> and the worker continues executing even after its <span
+  data-x="dom-WorkerGlobalScope-closing">closing</span> flag was set to true.</p>
+
   <hr>
 
   <p>The <span>task source</span> for the tasks mentioned above is the <span>DOM manipulation task
@@ -97788,9 +97764,9 @@ enum <dfn>WorkerType</dfn> { "classic", "module" };
 
   <div w-nodev>
 
-  <p>The <dfn><code data-x="dom-Worker-terminate">terminate()</code></dfn> method, when invoked, must
-  cause the "<span>terminate a worker</span>" algorithm to be run on the worker with which the object
-  is associated.</p>
+  <p>The <dfn><code data-x="dom-Worker-terminate">terminate()</code></dfn> method, when invoked,
+  must cause the <span>terminate a worker</span> algorithm to be run on the worker with which the
+  object is associated.</p>
 
   <p><code>Worker</code> objects act as if they had an implicit <code>MessagePort</code> associated
   with them. This port is part of a channel that is set up when the worker is created, but it is not
@@ -98112,8 +98088,7 @@ interface <dfn>NavigatorConcurrentHardware</dfn> {
 
       <p class="note"><var>script</var> will run until it either returns, fails to parse, fails to
       catch an exception, or gets <span data-x="abort a running script">prematurely aborted</span>
-      by the "<span>kill a worker</span>" or "<span>terminate a worker</span>" algorithms defined
-      above.</p>
+      by the <span>terminate a worker</span> algorithm defined above.</p>
 
       <p>If an exception was thrown or if the script was <span data-x="abort a running
       script">prematurely aborted</span>, then abort all these steps, letting the exception or