Squashed commit of the following:
commit 4bc40d9178
Author: Andrea Faulds <ajf@ajf.me>
Date: Sun Mar 20 02:20:28 2016 +0000
Update spec for invalid numeric strings
commit 2461e4f738
Author: Andrea Faulds <ajf@ajf.me>
Date: Wed Feb 24 16:53:26 2016 +0000
Updated tests for invalid numeric strings
* Clarify what whitespace is supported - this is not the same as
the white-space production.
* Clarify that a sign is supported (which is not the case for
the normal int/float productions)
* Clarify that we only support decimal digits or float literals
