Remove CodeMirror specific code

Authored by Pastakhov on May 2 2017, 6:18 AM.


Remove CodeMirror specific code

Seems CodeMirror should not be used with the MobileFrontend extension
since mobile devices should use the simplest editor only.

This code was introduced by I1d5dd5a0896c4f32954d9b948cc21c9406898f45
for a no longer used feature.

This code prevents wikis enabling CodeMirror on wikis which use
MobileFrontend REL1_29.
See https://www.mediawiki.org/wiki/Topic:Tzc99sm354p46l8u

Change-Id: I14ad8cbf5710e0e1df886f2c82b6f01f30381acc
(cherry picked from commit a0c7b4cb8ca9d68b3ca95d9b2189b02587e29f9f)