Fixes w.r.t travis-ci.org builds

In build travis-ci.org/marijnh/CodeMirror/builds/5063554 the build
system complained about:

    * rst.js: Unused argument options (1:53)
    * rst.js: Unused var rx_SEPA (36:8)
    * rst.js: Unused var rx_NAME_WWS (43:8)
    * rst.js: Unused var rx_REF_NAME (45:8)
    * rst.js: Unused var rx_TEXT1 (48:8)
    * rst.js: Unused argument state (535:33)

Should be fixed now (all warnings).