FAST_VRP uses a non-ranger gori_on_edge routine to calculate the full 
set of SSA ranges that can be calculated on an edge.  It allows an 
optional  outgoing_edge_range object if one wanted to use switches.  
This is now integrated with the gori () method of a range_query, and is 
no longer needed.

Bootstrapped on x86_64-pc-linux-gnu with no regressions.  Pushed.

Andrew