[FIXED JENKINS-25897] Add range check for H(X-Y) syntax

Do we need to retain backwards compatibility with this class?

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New and improved:

![screen shot](https://cloud.githubusercontent.com/assets/1831569/5533276/e625fe72-8a44-11e4-9a26-0d96900a3fd4.png)

@jglick Right, thanks for the info. (I wrote the test like this because I just copied that from `hashSkips()`.)