The test needed to be rewritten as we can't have the 3 warning messages
at the same time (see https://hg.mozilla.org/mozilla-central/rev/084f217c4d49#l1.76
and https://hg.mozilla.org/mozilla-central/diff/817eb00ba702/toolkit/components/passwordmgr/InsecurePasswordUtils.jsm#l1.106).
This wasn't picked up by the old frontend test because it is disabled.
In order to test the different warning messages we open 3 different pages
which log the appropriate warning.
MozReview-Commit-ID: Gqa8GrMh8iR
--HG--
rename : devtools/client/webconsole/new-console-output/test/mochitest/test-iframe-762593-insecure-form-action.html => devtools/client/webconsole/new-console-output/test/mochitest/test-iframe-insecure-form-action.html
rename : devtools/client/webconsole/new-console-output/test/mochitest/test-iframe-762593-insecure-frame.html => devtools/client/webconsole/new-console-output/test/mochitest/test-insecure-frame.html
rename : devtools/client/webconsole/new-console-output/test/mochitest/test-bug-762593-insecure-passwords-web-console-warning.html => devtools/client/webconsole/new-console-output/test/mochitest/test-insecure-passwords-web-console-warning.html
extra : rebase_source : 2afb77cb3dcf0f8df5116b7e7d85030a52bc0bc2