move post-GC WeakMap iterator specs to TruffleRuby-specific specs
move post-GC WeakMap iterator specs to TruffleRuby-specific specs


ruby/spec,nobu/rubyspec,eregon/rubyspec,nobu/rubyspec,nobu/rubyspec,ruby/spec,ruby/spec,eregon/rubyspec,eregon/rubyspec