This bug also renames the support file, and create a dedicated one for the child iframe.
An helper method is created to only wait for a single message with given text in it, as
well as returning an array of matched message in waitForMessages (we were returning the
result of setting the listener, which I doubt is useful for any test.
MozReview-Commit-ID: Gz7zqX825oR
--HG--
rename : devtools/client/webconsole/new-console-output/test/mochitest/browser_webconsole_autocomplete_crossdomain_iframe.js => devtools/client/webconsole/new-console-output/test/mochitest/browser_jsterm_autocomplete_crossdomain_iframe.js
rename : devtools/client/webconsole/new-console-output/test/mochitest/test-bug-989025-iframe-parent.html => devtools/client/webconsole/new-console-output/test/mochitest/test-iframe-parent.html
extra : rebase_source : aeef146dbe78e375e259cba96c3ab96287cb076a