[REPLCompletions] isdefined_globalref missing

[vtjnash]

isdefined_globalref was added by @Keno here:

julia/stdlib/REPL/src/REPLCompletions.jl

Lines 611 to 612 in d5442db

	if isdefined_globalref(g)
	return Const(ccall(:jl_get_globalref_value, Any, (Any,), g))

but deleted by @Keno here: 7f99e95

I'm unaware of why this code path exists if it is not reached in testing (@aviatesk in 98988d8)