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`.
When a node is removed from the DOM tree, its paintable needs to be
removed to ensure that it is not used to obtain sizes that are no
longer valid.
This change enables the ResizeObserver to send a notification if a node
is removed, as it should, because a removed node now has a size of zero
It should be okay to nullify pointers without concerning
parent/sibling/child relationships because the layout and paintable
trees will be rebuilt following any DOM mutation anyway.
