Allow `{`, `}` and `;` in Stylus
Allow `{`, `}` and `;` in Stylus

- Braces are allowed unconditionally as they are legal on top level
- Semicolon is allowed at the end of an attribute value for which
  there's no special mode started right after the attribute
- The value mode illegalizes the dot (`.`) as it's a probable case
  for other languages and seems to be illegal in Stylus
- `def` keyword added to avoid cross-detection with Gradle

Fixes #1028.

sourrust/highlight.js,palmin/highlight.js,teambition/highlight.js,highlightjs/highlight.js,MakeNowJust/highlight.js,carlokok/highlight.js,palmin/highlight.js,aurusov/highlight.js,StanislawSwierc/highlight.js,Sannis/highlight.js,isagalaev/highlight.js,palmin/highlight.js,carlokok/highlight.js,lead-auth/highlight.js,isagalaev/highlight.js,highlightjs/highlight.js,sourrust/highlight.js,highlightjs/highlight.js,MakeNowJust/highlight.js,MakeNowJust/highlight.js,carlokok/highlight.js,StanislawSwierc/highlight.js,sourrust/highlight.js,bluepichu/highlight.js,aurusov/highlight.js,teambition/highlight.js,bluepichu/highlight.js,Sannis/highlight.js,bluepichu/highlight.js,carlokok/highlight.js,Sannis/highlight.js,highlightjs/highlight.js,aurusov/highlight.js,teambition/highlight.js