* Update plugins/codemirror-editor from branch 'master'
to f72905bb83cb9d97781da110bd3ad88c2193ed7e
- Remove some unneeded themes/languages
These are not supported by the version of CodeMirror hosted internally
at Google, and are also not currently used.
Change-Id: Ic91267b8e3a7b17f1dcd8f66c61c0cd08ede1703