scimoz: move device pixels -> CSS pixels scaling to JS; fix direction.
http://bugs.activestate.com/show_bug.cgi?id=102105

We were scaling in the wrong direction for gecko -> scintilla

(integrated from komodo (trunk) change 83641 by marky)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@14178 b87d16e7-d29f-4ee1-b5ec-817d645d335f