Allow negative enum ids even if super inefficient (encodes as 10 byte…

…s), fixes #499, fixes #500 [ci skip]

src/parse.js

@@ -357,7 +357,7 @@ function parse(source, root) {
             throw illegal(token, s_name);
         var name = token;
         skip("=");
-        var value = parseId(next());
+        var value = parseNumber(next());
         parseInlineOptions(parent.values[name] = new Number(value)); // eslint-disable-line no-new-wrappers
     }