Reinforce readToken function

[dota17]

Add case "+" in readToken to allow it to read explicit positive number token.

[baylesj]

What is the use case for this? "+" tokens are not part of ECMAScript, RFC 7159, or json.org grammars. Is someone wanting this?

[dota17]

What is the use case for this? "+" tokens are not part of ECMAScript, RFC 7159, or json.org grammars. Is someone wanting this

In some special usage scenarios, like the dial codes {"BOSTON" : +1-617}, we do need to parse these cases, so we can use this case with the switch allowSpecialFloats_, just like we deal with NaN or Infinity.

[baylesj]

For dial codes, I would expect string representation, e.g.

"BOSTON": "+1-617"

Since 1-617 isn't a valid number anyway.

I still don't think we need this. Do we have clients wanting this? I'm especially concerned because if +Infinity is different than Infinity, we don't appear to preserve the "+" after parsing.