Remove step 4 of invoke idle callbacks algorithm.

Now that the event loop directly calls the start an idle period algorithm
each time it spins and the idle period conditions true, we no longer need
to call after having invoked idle callbacks.

index.html

@@ -455,8 +455,8 @@ <h2>The <code><dfn>IdleDeadline</dfn></code> interface</h2>
       <p>When the <code><dfn>timeRemaining</dfn>()</code> method is invoked on
       an <a>IdleDeadline</a> object it MUST return the remaining duration before
       the deadline expires as a <a>DOMHighResTimeStamp</a>, which SHOULD be
-      enough to allow measurement while preventing timing attack - see 
-      "Privacy and Security" section of [[HR-TIME]]. This value is calculated 
+      enough to allow measurement while preventing timing attack - see
+      "Privacy and Security" section of [[HR-TIME]]. This value is calculated
       by performing the following steps:</p>
       <ol>
         <li>Let <var>now</var> be a <a>DOMHighResTimeStamp</a> representing
@@ -551,9 +551,9 @@ <h2>Invoke idle callbacks algorithm</h2>
       <p>The <dfn>invoke idle callbacks algorithm</dfn>:</p>
       <ol>
         <li>If the user-agent believes it should end the idle period early due
-        to newly scheduled high-priority work, skip to step 4.
+        to newly scheduled high-priority work, return from the algorithm.
         <li>Let <var>now</var> be the current time.</li>
-        <li>If <var>now</var> is less than <var>deadline</var> and the 
+        <li>If <var>now</var> is less than <var>deadline</var> and the
         <var>window</var>'s <a>list of runnable idle callbacks</a> is not empty:
           <ol>
             <li>Pop the top <var>callback</var> from <var>window</var>'s
@@ -572,16 +572,11 @@ <h2>Invoke idle callbacks algorithm</h2>
             algorithm</li>
           </ol>
         </li>
-        <li>Otherwise, if either the <var>window</var>'s <a>list of idle request
-        callbacks</a> or it's <a>list of runnable idle callbacks</a> are
-        not empty, <a>queue a task</a> which performs the steps in the <a>start
-        an idle period algorithm</a> algorithm with <var>window</var> and as a
-        parameter.</li>
       </ol>
       <p class="note">The user agent is free to end an idle period early, even
-      if <var>deadline</var> has not yet occurred, by deciding to skip from step
-      1 directly to step 4. For example, the user agent may decide to do
-      this if it determines that higher priority work has become runnable.</p>
+      if <var>deadline</var> has not yet occurred, by deciding return from the
+      algorithm in step 1. For example, the user agent may decide to do this
+      if it determines that higher priority work has become runnable.</p>
     </section>
     <section>
       <h2>Invoke idle callback timeout algorithm</h2>