BasicSurface: another round of reductions on Surface that were pass-through functions to the underlying BufferStream, and don't really make sense if a Surface can have more than one buffer stream.
Specifically, remove from Surface (still present on Bufferstream)
allow_framedropping()
force_requests_to_complete()
pixel_format().
Approved by PS Jenkins bot, Alberto Aguirre, Alexandros Frantzis, Alan Griffiths.