         c = o.combinator;
          s = o.value;  
        }
        return c + s;
      });
      return selector;
    }

    function transformCompoundSelector(selector, combinator, scope, hostScope) {
      // replace :host with host scoping class
      var jumpIndex = selector.search(SCOPE_JUMP);
      if (selector.indexOf(HOST) >=0) {
        // :host(...)
        selector = selector.replace(HOST_PAREN, function(m, host, paren) {
          return hostScope + paren;
        });
        