Revert "Fixed DoubleToSingle in Jit64 and JitIL."

The Jit code was actually correct, the only problem were the calls to
the broken interpreter code. Keeping this in the history in case we ever
need an alternative assembler implementation of ConvertDoubleToSingle()
again.

This reverts commit 42ac7fbc598c8d3ea020810efde025c516e5299f.