Add ABuffer support to SkipCutBuffer

Add support for ABuffer to SkipCutBuffer, and make it (re)allocate an
appropriately sized buffer when needed, rather then relying on the
caller to tell it ahead of time how big the buffers are going to be.

Change-Id: I8b5c9ba5dd2fc13ef8870b7d4fe93a1bfdc7a626