Update lt_ie9.css.scss

fiese 'rake assets:precompile' errors;)
Make Rich Text Editor Insert <br> tags in IE 11

IE 11 was detected as gecko, causing the line break fix implemented in
wysihtml5 not to be applied.
Merge pull request #92 from tyranni/master

Adds missing "pageflow"-prefix to url in lt_ie9.css.scss
Merge pull request #91 from tf/ie11-wysihtml5

Make Rich Text Editor Insert <br> tags in IE 11