golang.org/cl/10800 add pos parameter to Eval; remove New, EvalNode
followed by several cleanups/follow-up fixes:
golang.org/cl/10992 remove global vars in test
golang.org/cl/10994 remove unused scope parameter from NewSignature
golang.org/cl/10995 provide full source file extent to file scope
golang.org/cl/10996 comment fix in resolver.go
golang.org/cl/11004 updated cmd/vet
golang.org/cl/11042 be robust in the presence of incorrect/missing position info
Fixes #9980.
Change-Id: Id4aff688f6a399f76bf92b84c7e793b8da8baa48
Reviewed-on: https://go-review.googlesource.com/11122 Reviewed-by: Alan Donovan <adonovan@google.com>