Apply testharness.js to non-pixel web tests from animations/events

This CL removes js-test.js and dumpAsText and applies testharness.js
from test files in animations/events.

Bug: 936364
Change-Id: I271a25ac26685324388b9c131e924d0188aea7c3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1530289
Reviewed-by: Kent Tamura <tkent@chromium.org>
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Julie Jeongeun Kim <jkim@igalia.com>
Cr-Commit-Position: refs/heads/master@{#643288}
16 files changed