Remove compound microtasks

Implementations do not have this concept and treat calling mutation observers and dispatching slotchange events as a microtask that happens to do quite a few things.

Author: annevk

source

@@ -90008,17 +90008,7 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
 
   <p>Each <span>event loop</span> has a <dfn>microtask queue</dfn>. A <dfn
   data-export="">microtask</dfn> is a <span data-x="concept-task">task</span> that is originally to
-  be queued on the <span>microtask queue</span> rather than a <span>task queue</span>. There are two
-  kinds of <span data-x="microtask">microtasks</span>: <dfn data-x="solitary callback
-  microtask" data-lt="solitary callback microtask" data-export="">solitary callback
-  microtasks</dfn>, and <dfn data-x="compound microtask" data-lt="compound microtask"
-  data-export="">compound microtasks</dfn>.</p>
-
-  <p class="note">This specification only has <span data-x="solitary callback microtask">solitary
-  callback microtasks</span>. Specifications that use <span data-x="compound microtask">compound
-  microtasks</span> have to take extra care to <span data-x="execute a compound microtask
-  subtask">wrap callbacks</span> to handle <span data-x="spin the event loop">spinning the event
-  loop</span>.</p>
+  be queued on the <span>microtask queue</span> rather than a <span>task queue</span>.</p>
 
   <p>When an algorithm requires a <span>microtask</span> to be <dfn data-x="queue a
   microtask" data-lt="queue a microtask" data-export="">queued</dfn>, it must be appended to the
@@ -90073,28 +90063,6 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    <li><p>Set the <span>performing a microtask checkpoint</span> flag to false.</p></li>
   </ol>
 
-  <p>If, while a <span>compound microtask</span> is running, the user agent is required to
-  <dfn data-export="">execute a compound microtask subtask</dfn> to run a series of steps, the user
-  agent must run the following steps:</p>
-
-  <ol>
-
-   <li><p>Let <var>parent</var> be the <span>event loop</span>'s <span>currently running
-   task</span> (the currently running <span>compound microtask</span>).</p></li>
-
-   <li><p>Let <var>subtask</var> be a new <span data-x="concept-task">task</span> that
-   consists of running the given series of steps. The <span>task source</span> of such a
-   <span>microtask</span> is the <span>microtask task source</span>. This is a <dfn>compound
-   microtask subtask</dfn>.</p></li>
-
-   <li><p>Set the <span>event loop</span>'s <span>currently running task</span> to <var>subtask</var>.</p></li>
-
-   <li><p>Run <var>subtask</var>.</p></li>
-
-   <li><p>Set the <span>event loop</span>'s <span>currently running task</span> back to <var>parent</var>.</p></li>
-
-  </ol>
-
   <hr>
 
   <p>When an algorithm running <span>in parallel</span> is to <dfn>await a stable state</dfn>, the
@@ -90119,19 +90087,11 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
   <p>When an algorithm says to <dfn>spin the event loop</dfn> until a condition <var>goal</var> is met, the user agent must run the following steps:</p>
 
   <ol>
+   <li><p>Let <var>task</var> be the <span>event loop</span>'s <span>currently running
+   task</span>.</p></li>
 
-   <li>
-
-    <p>Let <var>task</var> be the <span>event loop</span>'s <span>currently running
-    task</span>.</p>
-
-    <p class="note">This might be a <span>microtask</span>, in which case it is a <span>solitary
-    callback microtask</span>. It could also be a <span>compound microtask subtask</span>, or a
-    regular <span data-x="concept-task">task</span> that is not a <span>microtask</span>. It will
-    <em>not</em> be a <span>compound microtask</span>.</p> <!-- well, not unless we messed up in the
-    speccing, anyway... -->
-
-   </li>
+   <li><p>Assert: <var>task</var> is a <span data-x="concept-task">task</span> or a
+   <span>microtask</span>.</p></li>
 
    <li><p>Let <var>task source</var> be <var>task</var>'s <span>task
    source</span>.</p></li>
@@ -90141,17 +90101,19 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
 
    <li><p>Empty the <span>JavaScript execution context stack</span>.</p></li>
 
-   <li><p><span>Perform a microtask checkpoint</span>.</p></li>
-
    <li>
+    <p><span>Perform a microtask checkpoint</span>.</p>
 
-    <p>Stop <var>task</var>, allowing whatever algorithm that invoked it to resume, but
-    continue these steps <span>in parallel</span>.</p>
+    <p class="note">If <var>task</var> is a <span>microtask</span> this step will be a no-op due to
+    the <span>performing a microtask checkpoint</span> flag being set.</p>
+   </li>
 
-    <p class="note">This causes one of the following algorithms to continue: the <span>event
-    loop</span>'s main set of steps, the <span>perform a microtask checkpoint</span> algorithm, or
-    the <span>execute a compound microtask subtask</span> algorithm.</p>
+   <li>
+    <p>Stop <var>task</var>, allowing whatever algorithm that invoked it to resume, but continue
+    these steps <span>in parallel</span>.</p>
 
+    <p class="note">This causes the <span>event loop</span>'s main set of steps or the <span>perform
+    a microtask checkpoint</span> algorithm to continue.</p>
    </li>
 
    <li><p>Wait until the condition <var>goal</var> is met.</p></li>
@@ -90164,7 +90126,6 @@ dictionary <dfn>PromiseRejectionEventInit</dfn> : <span>EventInit</span> {
    stack</var>.</p></li>
 
    <li><p>Return to the caller.</p></li>
-
   </ol>
 
   <hr>