The wpt test file (popover-dialog-initial-focus.html) has been merged to popver-focus.html
in upstream (https://github.com/web-platform-tests/wpt/commit/c5fd23342c88e3540eee13ffb42262c9dc085d1e).
However, with popover feature in Gecko still in development stage, we have a lot of failures
at popver-focus.html and the test result doesn't respsents (clearly) the effect of this chage.
Thus, we temporarily re-introduce the initial wpt test file that focuses on testing this change.
This test file will be removed once we fix other focus issues in the merged test file.