mozilla: drop mozilla 18 code

(integrated from komodo (trunk) change 84843 by toddw)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@14333 b87d16e7-d29f-4ee1-b5ec-817d645d335f
contentUtils: support mozilla 31

(integrated from komodo (trunk) change 84844 by toddw)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@14334 b87d16e7-d29f-4ee1-b5ec-817d645d335f