Revert "Remove test case for paired browsing since broken in WP4.9 and would not pass in AMP 1.4 (#3928)"
Revert "Remove test case for paired browsing since broken in WP4.9 and would not pass in AMP 1.4 (#3928)"

This reverts commit 2fdb6789

ampproject/amp-toolbox-php,ampproject/amp-toolbox-php