Add specification for scheduler.yield() method

Author: shaseley

spec/controlling-tasks.md

@@ -193,6 +193,15 @@ object |signal|, [=set/append=] |algorithm| to |signal|'s [=TaskSignal/priority
   1. Set |signal|'s [=TaskSignal/priority changing=] to false.
 </div>
 
+<div algorithm>
+  To <dfn>create a fixed priority unabortable task signal</dfn> given {{TaskPriority}} |priority|
+  and a |realm|.
+
+  1. Let |init| be a new {{TaskSignalAnyInit}}.
+  1. Set |init|["{{TaskSignalAnyInit/priority}}"] to |priority|.
+  1. Return the result of [=creating a dependent task signal=] from « », |init|, and |realm|.
+</div>
+
 ### Garbage Collection ### {#sec-task-signal-garbage-collection}
 
 A [=TaskSignal/dependent=] {{TaskSignal}} object must not be garbage collected while its

spec/patches.md

@@ -32,6 +32,9 @@ determine task execution order across [=scheduler task queues=] of the same {{Ta
 all {{Scheduler}}s associated with the same [=event loop=]. A timestamp would also suffice as long
 as it is guaranteed to be strictly increasing and unique.
 
+Add: An [=event loop=] has a <dfn for="event loop">current scheduling state</dfn> (a [=scheduling
+state=] or null), which is initialized to null.
+
 ### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#event-loop-processing-model">Event loop: processing model</a> ### {#sec-patches-html-event-loop-processing}
 
 Add the following steps to the event loop processing steps, before step 2:
@@ -56,3 +59,46 @@ Issue: The |taskQueue| in this step will either be a [=set=] of [=tasks=] or a [
 [=scheduler tasks=]. The steps that follow only [=set/remove=] an [=set/item=], so they are
 *roughly* compatible. Ideally, there would be a common task queue interface that supports a `pop()`
 method that would return a plain [=task=], but that would involve a fair amount of refactoring.
+
+### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#hostmakejobcallback">HostMakeJobCallback(callable)</a> ### {#sec-patches-html-hostmakejobcallback}
+
+Add the following before step 5:
+
+  1. Let |state| be the [=incumbent realm=]'s [=realm/agent=]'s associated [=event loop=]'s
+     [=event loop/current scheduling state=].
+
+Modify step 5 to read:
+
+ 1. Return the <span>JobCallback Record</span> { `[[Callback]]`: <var ignore=''>callable</var>,
+    `[[HostDefined]]`: { `[[IncumbentSettings]]`: <var ignore=''>incumbent settings</var>,
+    `[[ActiveScriptContext]]`: <var ignore=''>script execution context</var>,
+    `[[SchedulingState]]`: |state| } }.
+
+### <a href="https://html.spec.whatwg.org/multipage/webappapis.html#hostcalljobcallback">HostCallJobCallback(callback, V, argumentsList)</a> ### {#sec-patches-html-hostcalljobcallback}
+
+Add the following steps before step 5:
+
+  1. Let |event loop| be the [=incumbent realm=]'s [=realm/agent=]'s associated [=event loop=].
+  1. Set |event loop|'s [=event loop/current scheduling state=] to
+     <var ignore=''>callback</var>.`[[HostDefined]]`.`[[SchedulingState]]`.
+
+Add the following after step 7:
+
+  1. Set |event loop|'s [=event loop/current scheduling state=] to null.
+
+## <a href="https://w3c.github.io/requestidlecallback/">`requestIdleCallback()`</a> ## {#sec-patches-requestidlecallback}
+
+### <a href="https://w3c.github.io/requestidlecallback/#invoke-idle-callbacks-algorithm">Invoke idle callbacks algorithm</a> ### {#sec-patches-invoke-idle-callbacks}
+
+Add the following step before step 3.3:
+
+  1. Let |realm| be <var ignore=''> window's [=relevant realm=].
+  1. Let |state| be a new [=scheduling state=].
+  1. Set |state|'s [=scheduling state/priority source=] to the result of [=creating a fixed priority
+     unabortable task signal=] given "{{TaskPriority/background}}" and |realm|.
+  1. Let |event loop| be |realm|'s [=realm/agent=]'s associated [=event loop=].
+  1. Set |event loop|'s [=event loop/current scheduling state=] to |state|.
+
+Add the following after step 3.3:
+
+  1. Set |event loop|'s [=event loop/current scheduling state=] to null.