Match the css-syntax spec for +/**/1

"`<number-token>`, `<number-token>`, and `<dimension-token>` have been changed to include the preceding +/- sign as part of their value (rather than as a separate `<delim-token>` that needs to be manually handled every time the token is mentioned in other specs). The only consequence of this is that comments can no longer be inserted between the sign and the number."
http://dev.w3.org/csswg/css-syntax/#changes-css21