Convert editing/pasteboard/merge-after-delete*.html to use w3c test harness
This patch converts "editing/pasteboard/merge-after-delete*.html" to use w3c
test harness and consolidates into "merge_after_delete.html" to simplify test
case for ease of maintenance.
This patch is a preparation of getting rid of grammar checking feature.
BUG=
619452
TEST=n/a; this patch changes a test file
Committed:
https://crrev.com/1004d071d629d70592d69700a5d388e1a526559e
Cr-Commit-Position: refs/heads/master@{#408027}