tests: html: add testcase for completions in invalid html files
http://bugs.activestate.com/show_bug.cgi?id=99976

(integrated from komodo (trunk) change 81285 by toddw)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@13386 b87d16e7-d29f-4ee1-b5ec-817d645d335f