[accelerometer] Why unrestricted double for acceleration readings?

dontcallmedom has just created a new issue for https://github.com/w3c/accelerometer:

== Why unrestricted double for acceleration readings? ==
When the spec was [switched from separate reading interface to include it in the main one](https://github.com/w3c/accelerometer/commit/a1b7d8584615f4c6031f7402f10cbd115ba9a91f), the types of the `x`, `y`, `z` attributes were switched to `**unrestricted** double` - what is the reasoning behind the change? I didn't find anything related to `Infinity` in the spec, nor did I easily find any supporting model consideration in the generic sensor spec, nor in the motion sensors spec.

if there is a good reason, I think it should be documented, possibly in the 3 docs; if there isn't, 

Please view or discuss this issue at https://github.com/w3c/accelerometer/issues/23 using your GitHub account