scala/scala — pull request #2926 by paulp (2013-09-09 19:57:25+00:00)
Title: Noise reduction + minor enhance in TreeCheckers.

Misc irrelevant work, which I can only offer as-is. It lowers
the noise in -Ycheck:* output and performs some common sense
chillaxes like not screaming ERROR IN INTERNAL CHECKING! WE'RE
ALL GOING TO DIE! when a tree doesn't hit all nine points at
the Jiffy Tree.

You can see some reasonably well reduced symbol flailing if you run the included pending tests:
```test/partest --show-diff test/pending/pos/treecheckers```

```text
Out of scope symbol reference {
tree TypeTree Factory[Traversable]
position OffsetPosition test/pending/pos/treecheckers/c5.scala:3
with sym ClassSymbol Factory: Factory[CC]
and tpe ClassArgsTypeRef Factory[Traversable]
encl(1) ModuleSymbol object Test5
ref to AbstractTypeSymbol X ( )
}
```