Convert editing/insert-3778059-fix.html to use w3c test harness
This patch converts "editing/insert-3778059-fix.html" to use w3c test
harness to simplify test script and renames to "insert_between_block_quote.html"
to provide to provide a hint what this test script verifies, for improving
readability.
BUG=n/a
TEST=n/a; no behavior changes
Committed:
https://crrev.com/2ea5309093ffe5e8a96ab93f6bcc2fd3564a4b16
Cr-Commit-Position: refs/heads/master@{#414361}