static Set<S> tokenIndexWithoutIfclass_forStdClasses(L<S> tok) {
  new HashSet<S> set;
  int n = l(tok);
  int level = 0;
  for (int i = 1; i < n; i += 2) {
    S t = tok.get(i);
    if (eqOneOf_twoNonNullStrings(t, "ifclass", "ifndef")) ++level;
    else if (eqOneOf_twoNonNullStrings(t, "endif", "endifndef")) --level;
    else if (level <= 0 && startsWithJavaIdentifierStart(t)
      && !eqOneOf_twoNonNullStrings(get(tok, i-2), ".", "virtual"))
        set.add(t);
  }
  ret set;
}

Began life as a copy of #1007325