719adb851d
Because individual <option> elements are painted and represented in the
DOM when they belong to a <select multiple> list, the center point of
the list might be one of the options.
To take this into account, we perform an inclusive descendant check
(DOMElement.contains) to see if the <option> element is a descendant of
the container <select> element.
In the case the targetted element is the element itself, the test will
still pass since it is an _inclusive_ descendant check. In other words,
containerEl.contains(tree[0]), if tree[0] is equal to containerEl,
will pass.
The relevant specification changes were made in
40abcefd6a.
MozReview-Commit-ID: ORX8zLxQJ
Common testing tools for mozilla codebase projects, test suite definitions for automated test runs, tests that don't fit anywhere else, and other fun stuff