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`.
Ideally we would not create a layout node at all for these elements so
that every layout node would always have a paintable associated with it.
But for now, to fix the crash, just leave a FIXME and special case this
element.
Also leave a VERIFY to make it easier to debug this type of crash in the
future.
Fixes a crash seen on codecov.io for my 'patch' project.