Remove "DOM Event Architecture" from spec

[garykac]

The section in question: https://w3c.github.io/uievents/#dom-event-architecture

This section give a non-normative summary of event dispatch and event flow, but it also contains info that can cause confusion (eg: "default actions"). Much of this is normatively specified in DOM spec, and the useful bits need to be moved into the appropriate algorithm.

• [x] 3.1. Event dispatch and DOM event flow
  • [x] Delete this section. This is defined normatively in the DOM spec. No need to provide competing, non-normative definitions.
  • [x] It is worthwhile to copy this into a separate document before deleting?
    • [x] If so, update the links so that they point to the proper definitions.
• [x] 3.2. Default actions and cancelable events
  • [x] Delete this section. "Default actions" aren't really a defined thing and cancelability is complicated and needs to be defined as part of the algorithm for each event.
  • See https://github.com/w3c/uievents/issues/104 and https://github.com/w3c/uievents/issues/22
• [x] 3.3. Synchronous and asynchronous events
  • [x] Delete this section. Sync vs async needs to be part of the algorithm. This section just states that events can be either sync or async.
• [ ] 3.4. Trusted events
  • [ ] Move info about the click event and "default action" into the algorithm for MouseEvents.
  • [x] Delete this section. isTrusted and friends are all defined properly in DOM. This spec should simply be using isTrusted in the algorithms.
• [x] 3.5. Activation triggers and behavior
  • [x] Delete this section. It basically says that "activation behaviors" can happen in response to "activation triggers", which is not terribly insightful or useful. As stated elsewhere: these behaviors need to be defined in an algorithm.
• [ ] 3.6. Constructing Mouse and Keyboard Events
  • [ ] Move relevant parts into KeyboardEvent section
  • [x] Move relevant parts into MouseEvent section
  • [x] Delete this section.