Convert editing/pasteboard/pasteboard/paste-4038267-fix.html.html to use w3c test harness

This patch converts "editing/pasteboard/merge-end-blockquote.html" to use w3c
test harness and rename "insert_interchange_newline_crash.html" to to simplify
test files, since this test verifies "insertHTML" command instead of "paste".

This patch is a preparation of getting rid of grammar checking feature.

BUG=619452
TEST=n/a; this patch changes a test file

Review-Url: https://codereview.chromium.org/2184623002
Cr-Commit-Position: refs/heads/master@{#407999}
8 files changed