Began addressing feedback from bug #24697

Started rewriting steps to apply an orientation lock algorithm as per Bugzilla bug [24697](https://www.w3.org/Bugs/Public/show_bug.cgi?id=24697). 

It reworks the way the promise are resolved/rejected and the "pending promise" which is in the asynchronous task. 
I guess you can have the entire thing in one line:
```html
<li>If <var>pending promise</var> is not <code>null</code>, reject <var>pending-promise</var> with
<code>DOMException</code> whose name is <code>AbortError</code>.</li>
```