Bug 1584282: Remove forgotten debug statement within test_bug629172.html from Bug 1497200. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D47307

--HG--
extra : moz-landing-system : lando

editor/libeditor/tests/test_bug629172.html

@@ -23,7 +23,6 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=629172
 /** Test for Bug 629172 **/
 SimpleTest.waitForExplicitFinish();
 SimpleTest.waitForFocus(async function() {
-  dump("\n\n XXX TEST STARTS HERE \n\n");
   await SpecialPowers.pushPrefEnv({
     set: [["test.events.async.enabled", true]],
   });