And, I'm thinking you just hadn't yet gotten to the parts which made me move it to SingleType. With your patch:
```
scalac -d /tmp test/files/pos/context.scala 
error: scala.reflect.internal.Types$TypeError: type mismatch;
 found   : Symbols.this.$outer.type
 required: SymbolWrapper.this.type
	at scala.tools.nsc.typechecker.Contexts$Context.issueCommon(Contexts.scala:546)
	at scala.tools.nsc.typechecker.Contexts$Context.issue(Contexts.scala:551)
	at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueTypeError(ContextErrors.scala:97)
	at scala.tools.nsc.typechecker.ContextErrors$ErrorUtils$.issueNormalTypeError(ContextErrors.scala:86)
```
There were a handful of others as well.