remove InteractiveUtils.dumptype (#42093)

It was broken (`TypeName.abstract`) is not defined anymore, so clearly has
no users nor tests and can simply be deleted at this point.

stdlib/InteractiveUtils/src/InteractiveUtils.jl

@@ -279,74 +279,6 @@ function supertypes(T::Type)
  return S === T ? (T,) : (T, supertypes(S)...)
 end
 
-# dumptype is for displaying abstract type hierarchies,
-# based on Jameson Nash's typetree.jl in https://github.com/JuliaArchive/Examples
-function dumptype(io::IO, @nospecialize(x), n::Int, indent)
- print(io, x)
- n == 0 && return # too deeply nested
- isa(x, DataType) && x.name.abstract && dumpsubtypes(io, x, Main, n, indent)
- nothing
-end
-
-directsubtype(a::DataType, b::DataType) = supertype(a).name === b.name
-directsubtype(a::UnionAll, b::DataType) = directsubtype(a.body, b)
-directsubtype(a::Union, b::DataType) = directsubtype(a.a, b) || directsubtype(a.b, b)
-# Fallback to handle TypeVar's
-directsubtype(a, b::DataType) = false
-function dumpsubtypes(io::IO, x::DataType, m::Module, n::Int, indent)
- for s in names(m, all = true)
- if isdefined(m, s) && !isdeprecated(m, s)
- t = getfield(m, s)
- if t === x || t === m
- continue
- elseif isa(t, Module) && nameof(t) === s && parentmodule(t) === m
- # recurse into primary module bindings
- dumpsubtypes(io, x, t, n, indent)
- elseif isa(t, UnionAll) && directsubtype(t::UnionAll, x)
- dt = unwrap_unionall(t)
- println(io)
- if isa(dt, DataType) && dt.name.wrapper === t
- # primary type binding
- print(io, indent, " ")
- dumptype(io, dt, n - 1, string(indent, " "))
- else
- # aliases to types
- print(io, indent, " ", m, ".", s, "{")
- tvar_io::IOContext = io
- tp = t
- while true
- show(tvar_io, tp.var)
- tvar_io = IOContext(tvar_io, :unionall_env => tp.var)
- tp = tp.body
- if isa(tp, UnionAll)
- print(io, ", ")
- else
- print(io, "} = ")
- break
- end
- end
- show(tvar_io, tp)
- end
- elseif isa(t, Union) && directsubtype(t::Union, x)
- println(io)
- print(io, indent, " ", m, ".", s, " = ", t)
- elseif isa(t, DataType) && directsubtype(t::DataType, x)
- println(io)
- if t.name.module !== m || t.name.name != s
- # aliases to types
- print(io, indent, " ", m, ".", s, " = ")
- show(io, t)
- else
- # primary type binding
- print(io, indent, " ")
- dumptype(io, t, n - 1, string(indent, " "))
- end
- end
- end
- end
- nothing
-end
-
 # TODO: @deprecate peakflops to LinearAlgebra
 export peakflops
 """