String to number conversion: Differences between JavaRosa and Webforms

[brontolosone]

While working on #49, I stumbled upon some implementation differences between webforms and JavaRosa, that came about while thinking about "how and why does JR allow a randomization seed from a node with text, is that intentional or accidental, and should Webforms do the same" (so far I only have answers to #1 and maybe #2). Anyway:

The equivalent of a JS Number as used in Webforms is the Java Double. Same thing, same precision, so in theory this should allow identical outcomes on both platforms.

• JavaRosa implementation (think of it as a toDouble, as that's what it does)

• The correspondent code site in Webforms might be here

Evidently the JR implementation is much more extensive; and there's talk about "xpath type conversion rules" — which I haven't looked up, but those sound as if they could be relevant for webforms.

Poignantly, JR allows for "123,123" -> 123.123, while Webforms makes this a NaN.
Conversely, Webforms allows "0x12" -> 18, while JR would make this a NaN.

The question is thus: which one (if any) of the two is right? And if JR is right, what'd be the appropriate site for the Webforms implementation of same?