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 would previously not return a RadioNodeList in the curious case where
a named item resolves to two different elements within the form.
This was not a problem when calling namedItem directly in the IDL as
named_item_or_radio_node_list shadows named_item but is exposed when
calling the property through array bracket notation (as an example).
Fix this, and add a bunch more tests to cover
HTMLFormControlsCollection.