domxpath: Add a test for lang()

Bug: crbug.com/627682
Change-Id: I6f7a7c39c5d7fe0c0e4ba01613bd38886216c918
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1574874
Commit-Queue: Kent Tamura <tkent@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#652822}
1 file changed