Define speculative HTML parsing (WIP)

source

@@ -111086,6 +111086,8 @@ document.body.appendChild(text);
       invocations of the tokenizer, yielding control back to the caller. (Tokenization will resume
       when the caller returns to the "outer" tree construction stage.)</p>
 
+      <p class="XXX">Speculatively parse the remainder of the document.write string here?</p>
+
       <p class="note">The tree construction stage of this particular parser is <a
       href="#nestedParsing">being called reentrantly</a>, say from a call to <code
       data-x="dom-document-write">document.write()</code>.</p>
@@ -111101,6 +111103,9 @@ document.body.appendChild(text);
        <li><p>Let <var>the script</var> be the <span>pending parsing-blocking
        script</span>. There is no longer a <span>pending parsing-blocking script</span>.</p></li>
 
+       <li><p><span>Start the speculative HTML parser</span> for this instance of the HTML
+       parser.</p></li>
+
        <li><p>Block the <span data-x="tokenization">tokenizer</span> for this instance of the
        <span>HTML parser</span>, such that the <span>event loop</span> will not run <span
        data-x="concept-task">tasks</span> that invoke the <span
@@ -111122,6 +111127,9 @@ document.body.appendChild(text);
         <code>Document</code>.</p>
        </li>
 
+       <li><p><span>Stop the speculative HTML parser</span> for this instance of the HTML
+       parser.</p></li>
+
        <li><p>Unblock the <span data-x="tokenization">tokenizer</span> for this instance of the
        <span>HTML parser</span>, such that <span data-x="concept-task">tasks</span> that invoke the
        <span data-x="tokenization">tokenizer</span> can again be run.</p></li>
@@ -112657,6 +112665,14 @@ document.body.appendChild(text);
 
   </div>
 
+  <div w-nodev>
+
+  <h4>Speculative HTML parsing</h4>
+
+  <p class="XXX"><dfn>Speculative HTML parser</dfn>, <dfn>start the speculative HTML parser</dfn>,
+  <dfn>stop the speculative HTML parser</dfn>...</p>
+
+  </div>
 
   <div w-nodev>
 
@@ -112781,6 +112797,9 @@ document.body.appendChild(text);
    <li><p>Throw away any pending content in the <span>input stream</span>, and discard any future
    content that would have been added to it.</p></li>
 
+   <li><p>If there is an active <span>speculative HTML parser</span>, <span>stop the speculative
+   HTML parser</span> for this HTML parser.</p></li>
+
    <li><p>Set the <span>current document readiness</span> to "<code data-x="">interactive</code>"<!--
    this immediately fires an event -->.</p></li>