Convert editing/paste-text-019.html to use w3c test harness

This patch converts "editing/paste-text-019.html" to use w3c
test harness to simplify test files and rename to
"paste_text_with_text_transform.html" to denote what this test file does.

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/2184033002
Cr-Commit-Position: refs/heads/master@{#408060}
8 files changed