fixup! Event: Increase robustness of an inner native event in leverag…

…eNative

src/event.js

@@ -519,10 +519,24 @@ function leverageNative( el, type, isSetup ) {
  var result,
  saved = dataPriv.get( this, type );
 
+ // This controller function is invoked under multiple circumstances,
+ // differentiated by the stored value in `saved`:
+ // 1. For an outer synthetic `.trigger()`ed event (detected by
+ // `event.isTrigger & 1` and non-array `saved`), it records arguments
+ // as an array and fires an [inner] native event to prompt state
+ // changes that should be observed by registered listeners (such as
+ // checkbox toggling and focus updating), then clears the stored value.
+ // 2. For an [inner] native event (detected by `saved` being
+ // an array), it triggers an inner synthetic event, records the
+ // result, and preempts propagation to further jQuery listeners.
+ // 3. For an inner synthetic event (detected by `event.isTrigger & 1` and
+ // array `saved`), it prevents double-propagation of surrogate events
+ // but otherwise allows everything to proceed (particularly including
+ // further listeners).
+ // Possible `saved` data shapes: `[...], `{ value }`, `false`.
  if ( ( event.isTrigger & 1 ) && this[ type ] ) {
 
  // Interrupt processing of the outer synthetic .trigger()ed event
- // Detect `saved` of shape `{ value }` and `false`.
  if ( !saved.length ) {
 
  // Store arguments for use when handling the inner native event
@@ -559,9 +573,8 @@ function leverageNative( el, type, isSetup ) {
  event.stopPropagation();
  }
 
- // If this is a native event triggered above, everything is now in order
- // Fire an inner synthetic event with the original arguments
- // Exclude `saved` of shape `{ value }` and `false`.
+ // If this is a native event triggered above, everything is now in order.
+ // Fire an inner synthetic event with the original arguments.
  } else if ( saved.length ) {
 
  // ...and capture the result