AccName: reconsider appending space between inline text nodes

[cookiecrook]

In review for WPT /accname/name/comp_text_node.html

<h2 class="ex" data-expectedlabel="heading label" data-testname="heading with text/comment/text nodes" id="labelTest1">
  heading<!-- with non-text node splitting concatenated text nodes -->label<!-- [sic] no extra spaces around first comment -->
</h2> 

WebKit results in PASS: expected "heading label" and got "heading label"
Chrome results in FAIL: expected "heading label" but got "headinglabel"

Discrepancy is that the AccName comp uses the term node, and these are two text nodes joined by a comment node and no additional whitespace.

Even if WebKit is to spec here, Chromium's implementation allows authors to choose whether they want the space, while WebKit always joins on a space, according to the spec. Worth revisiting?

Skipping this test in WPT for now.

• If this results in a spec change, please raise a new issue in AccName to update the WPT test, or
• If this results in no spec change, pleas assign back to me and I'll used this one to reinstate the test as written, confirming the WebKit behavior, not the Chromium behavior.

[cookiecrook]

Related to #205. I'm going to check in the WPT test using the Chrome behavior, since that's what the editors have indicated should happen, even though it's not in the spec yet.

[accdc]

Personally I would expect "headinglabel" to be correct, because a comment is not actually renderable as anything and is actually supposed to be entirely ignored within the rendered page structure, so there would be no value in including this for any type of additional processing with AccName. That would be like processing <input type="hidden"> which wouldn't make any sense either.

If this makes sense to others we can clarify it within the spec text.

[cookiecrook]

Okay. I've updated the tests to support your stated change here, so WebKit is currently failing the tests (to be linked once WPT is merged), despite it being the only implementation to match the spec. web-platform-tests/wpt#42407

Please update the spec soon to match this new expectation.