For example, in the following abbreviated test HTML:
<span>some text</span>
<script>println("whf")</script>
We would have to craft the expectation file to include the "some text"
segment, usually with some leading whitespace. This is a bit annoying,
and makes it difficult to manually craft expectation files.
So instead of comparing the expectation against the entire DOM inner
text, we now send the inner text of just the <pre> element containing
the test output when we invoke `internals.signalTextTestIsDone`.
We were generating click events always using the primary mouse button
instead of the provided button, and with the buttons field set to that
provided button.
This returns the secondary target of a mouse event. For `onmouseenter`
and `onmouseover` events, this is the EventTarget the mouse exited
from. For `onmouseleave` and `onmouseout` events, this is the
EventTarget the mouse entered to.
