internal/number: remove conversion code

We’ll base it on the code of big.Float instead.

Change-Id: Ibd3fb9ada614b05595aa824039f6dbc143263351
Reviewed-on: https://go-review.googlesource.com/36274
Run-TryBot: Marcel van Lohuizen <mpvl@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Nigel Tao <nigeltao@golang.org>
4 files changed