Review and possibly port Chromium accname tests into WPT

[cookiecrook]

From w3c/accname#190 (comment), @jaragunde wrote:

In case it's useful later, I created a list of the accname tests in Chromium and when they were added, so we can differentiate the ones that Joanmarie imported from the work group and the ones that were added later by Chromium devs. It also lists when the expectations were last modified, to know if the test needed changing from the original and why.

Info here: https://docs.google.com/spreadsheets/d/1cXaNgsraAQwVAfYPMuaeayoyAG-5pnztrMjewrK0mpY/edit?usp=sharing

Filing here because, after the other AccName tests in #3 are finished, we should review and incorporate any of the Chromium label tests if those cases weren't already included.