Drag/drop generates click events, but these aren't actually a click event intended to activate a control.
Therefore, we don't want to run accessibility checks for the target.
To achieve this, EventUtils.synthesizeDropAfterDragOver instructs AccessibilityUtils to ignore click events while the event is being sent.
This requires that EventUtils has the reference to AccessibilityUtils set by the browser test harness.
As such, some tests had to be adjusted so that they use EventUtils from the browser test scope, rather than loading their own copy of EventUtils.
Depends on D190004
Differential Revision: https://phabricator.services.mozilla.com/D185776
25f0d4edd4