Missing tasks in parallel steps in Payment Request API

While crawling Payment Request API, the following algorithms fire an event, or resolve or reject a Promise, within a step that runs in parallel without first queuing a task:

• The algorithm that starts with "The show(optional detailsPromise) method MUST act as follows:" resolves/rejects a promise directly in a step that runs in parallel
• The algorithm that starts with "The complete() method MUST act as follows:" resolves/rejects a promise directly in a step that runs in parallel
• The can make payment algorithm algorithm resolves/rejects a promise directly in a step that runs in parallel

See Dealing with the event loop in the HTML specification for guidance on how to deal with algorithm sections that run in parallel.

_{Cc @dontcallmedom @tidoust}

_{This issue was detected and reported semi-automatically by Strudy based on data collected in webref.}

Start with the Payment Request API algorithms beginning with “The show(optional detailsPromise) method MUST act as follows:”, “The complete() method MUST act as follows:”, and the can make payment algorithm. Read HTML’s “Dealing with the event loop” guidance first, then verify each parallel step that resolves or rejects a Promise. Done means all three algorithms queue the required task before those operations.