Tweaks to EchoTalkPageFunctionalTest
Tweaks to EchoTalkPageFunctionalTest

* Fix off-by-one counting
* Fix asserting properties on the wrong event (first one instead of
  last one), luckily they are identical

Change-Id: Ib1a02476554b29b2a1d0bfdfa89859d71d7691b1

wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo,wikimedia/mediawiki-extensions-Echo